This work addresses the scalability of power performance of AlGaN/GaN MODFETs with large gate per... more This work addresses the scalability of power performance of AlGaN/GaN MODFETs with large gate periphery, as necessary for microwave power devices. High-frequency largesignal characteristics of AlGaN/GaN MODFETs have been studied for devices with gate widths from 0.2 to 1 mm. 1-dB gain compression occurred at input power levels varying from-1 to +10dBm as the gate width increased, while gain remained almost constant at ~17dB. Output power density was maximum (1.3W/mm) for devices with 0.6mm gates and maximum output power (29.9dBm) occurred in devices with 1mm gates, while power-added-efficiency remained almost constant at ~30%. I. INTRODUCTION AlGaN/GaN heterojunction FETs grown by RF-assisted MBE have a high potential for highpower electronics as previously reported by the authors [1]. A record output power density of 3W/mm at 18GHz and 5.3W/mm at 10GHz [2] was recently obtained using AlGaN/GaN MODFETs. The DC and small-signal highfrequency performance of Al 0.3 Ga 0.7 N/GaN MODFETs...
Monolithic Integrated Circuit (MMIC) attenuators were realized for the first time. The MMICs empl... more Monolithic Integrated Circuit (MMIC) attenuators were realized for the first time. The MMICs employed AlGaN/GaN HEMTs fabricated by optical contact lithography (Lg=1µm) with high current gain (fT) and maximum power gain (fMAX) cutoff frequencies of 17 and 24GHz, respectively. The MMIC attenuators employing three 100µm-wide AlGaN/GaN HEMTs in π-configuration had minimum insertion of 4dB, high dynamic range (>30dB), and broadband operation (up to 18GHz). On-wafer power characterization at 8GHz confirmed successful operation of the GaN-based attenuator MMICs at power density exceeding 15W/mm. I.
— The design, fabrication, and experimental characteristics of InGaAs PIN diodes are presented fo... more — The design, fabrication, and experimental characteristics of InGaAs PIN diodes are presented for InP-based W-band monolithic integrated switches. The diodes with 10µm-diameter were used and showed a breakdown voltage of 17 V, a turnon voltage of 0.36 V, and a switching cutoff frequency of 6.3 THz. The monolithic integrated switches employed microstrip transmission lines and backside via holes for low-inductance signal grounding. A radial stub-based design was used for on-chip biasing, and the high-frequency characteristics of the switches were verified by on-wafer W-band testing. The SPST PIN monolithic switch demonstrated 25 dB isolation, 1.3 dB insertion loss, and 0.8 dB reflection loss at 83 GHz. I.
The DC and high frequency performance of AlGaN/GaN Heterojunction Bipolar Transistors (HBTs) is a... more The DC and high frequency performance of AlGaN/GaN Heterojunction Bipolar Transistors (HBTs) is analyzed using an enhanced drift-di€usion model and GaN/AlGaN material parameters, which were previously veri®ed by modeling experimental device characteristics. The emitter±base diode turn-on voltage is as high as 2.7 V while the collector and base ideality factors are 1.16 and 1.46 respectively. A DC current gain of b=15 is found at a collector current density of 2.5 kA/cm 2 and the gain is maintained at this value up to 4.1 kA/cm 2. The devices show a small o€set voltage of 0.5 V. A forward breakdown voltage BVCEO of 70 V is found for designs with collector doping of 5 10 16 cm �3. The current gain varied from 22 to 6 when the base doping was increased from 5 10 17 to 2 10 18 cm �3. At the same time, the maximum oscillation frequency fMAX increased from 3 to 6 GHz. A severe degradation of the current gain, fT, and fMAX was observed for HBT designs with a base thickness wider than 1000 ...
The GaN material parameters relevant to the negative di€erential resistance (NDR) devices are dis... more The GaN material parameters relevant to the negative di€erential resistance (NDR) devices are discussed, and their physical models based on the theoretical predictions and experimental device characteristics are introduced. Gunn diode design criteria were applied to design the GaN NDR diodes. A higher electrical strength of the GaN allowed operation with higher doping ( 1017 cm�3) and at a higher bias (90 V for a 3 µm thick diode). The transient hydrodynamic simulations were used to carry out the harmonic power analysis of the GaN NDR diode oscillators in order to evaluate their large-signal microwave characteristics. The GaAs Gunn diode oscillators were also simulated for a comparison and verification purposes. The dependence of the oscillation frequency and output power on the GaN NDR diode design and operating conditions are reported. It was found that, due to the higher electron velocities and reduced time constants, GaN NDR diodes o€ered twice the frequency capability of the Ga...
The frequency and power capability of GaN-based Gunn diodes is evaluated using transient hydrodyn... more The frequency and power capability of GaN-based Gunn diodes is evaluated using transient hydrodynamic simulations. GaN Gunn oscillators with 2µm-thick GaN Gunn diodes are predicted to have fundamental frequency of 148-162GHz and power density of>10 5 W/cm 2. Due to their high frequency and power characteristics, applications of these devices are envisaged for THz signal generation.
⎯ InP-based InGaAs PIN millimeterwave diodes were used to design and fabricate monolithic integra... more ⎯ InP-based InGaAs PIN millimeterwave diodes were used to design and fabricate monolithic integrated transmit-receive switches for W-band automotive applications. Coplanarwaveguide InGaAs PIN diode technology with reduced parasitics was employed for fabricating MMICs and yielded switches with high isolation and low insertion loss as shown by the performance of W-band single-pole double-throw switches. 77GHz SPDT switches demonstrated less than 1.35dB insertion loss, more than 43dB input-to-output isolation, and more than 30dB output-to-output crosstalk. W-band on-wafer large-signal characterization revealed no degradation of performance when the input power was increased to the maximum available level of +11dBm. I.
III-V Nitride Based MISFETs have been studied using AIN/GaN heterostructures grown by MOCVD at th... more III-V Nitride Based MISFETs have been studied using AIN/GaN heterostructures grown by MOCVD at the University of Michigan. MIS structures fabricated on such materials showed very low interface state density Dit values of -lx1011cm-2eV-1. The maximum drain current of AIN/GaN MISFETs made on these materials was greater than 700mA/mm, while drain-source breakdown was 30 V and drain-gate breakdown was 40V. Devices with a gate length of 2(j.m exhibited a peak transconductance of 136mS/mm at VGS=1V, which exceeds previously reported results.
Wide bandgap III-V nitride semiconductors are excellent candidates for high power applications an... more Wide bandgap III-V nitride semiconductors are excellent candidates for high power applications and superior power performance of AlGaN/GaN MODFETs has been reported recently [1]. Circuits designed for power applications such as power amplifiers, oscillators and mixers, operate under large-signal conditions and their performance can deviate significantly from small-signal predicted characteristics in case of frequency dependent device properties. It is consequently very important to understand and if possible control and suppress such dispersion effects. The low frequency output resistance (RDS) and transconductance (gm) dispersion characteristics of GaAs MESFETs [2]-[3] and GaAs as well as InP-based MODFETs [4]-[5] have been addressed by various groups. However, the dispersion characteristics of AlGaN/GaN MODFETs are not well understood at this point and significant interest exists in this area in order to explain dispersion between DC predicted and high–frequency measured power cha...
This paper demonstrates the design of high-isolation millimeter-wave monolithic integrated switch... more This paper demonstrates the design of high-isolation millimeter-wave monolithic integrated switches using MOCVD-grown InGaAs/InP PIN diodes as switching devices. W-band single-pole single-throw switch using double shunt diode topology allowed significant improvement of isolation while keeping insertion loss low. The SPST switch used two InGaAs PIN diodes and demonstrated better than 35dB isolation and 1.8dB insertion loss at 92GHz. A comparative analysis of single and double diode switch characteristics is treated together with the design and fabrication details. The power handling capability of the switches is also discussed.
GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing... more GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing Gunn design criteria applicable to this material system. Numerical simulations were used to carry out large-signal analysis of the GaN NDR diode oscillators in order to evaluate their potential for THz signal generation. It was found that, due to the higher electron velocity and reduced time constants involved in the diode operation, GaN NDR diodes offer significantly higher frequency and power capability than conventional GaAs Gunn diodes. Based on the performed analysis, THz signal generation using GaN-based NDR diodes was predicted. GaN NDR layer structures were grown by MOCVD. The fabrication technology and characterization techniques used for GaN NDR diode oscillators are presented.
GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing... more GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing Gunn design criteria applicable to this material system. Numerical simulations were used to carry out large-signal analysis of the GaN NDR diode oscillators in order to evaluate their potential for THz signal generation. It was found that, due to the higher electron velocity and reduced time constants involved in the diode operation, GaN NDR diodes offer significantly higher frequency and power capability than conventional GaAs Gunn diodes. Based on the performed analysis, THz signal generation using GaN-based NDR diodes was predicted. GaN NDR layer structures were grown by MOCVD. The fabrication technology and characterization techniques used for GaN NDR diode oscillators are presented.
We report on the measured performance of monolithic integrated mm-wave switching circuits which o... more We report on the measured performance of monolithic integrated mm-wave switching circuits which operate at Ka-Band. V-Band and W-Band as well as on a technology for multi-functional MMICs. The coplanar switches are using high-performance InGaAs PIN diodes as active switching elements. The focus of the illustrated measurement results is on the characteristics of the W-Band switches. The SPST (single-pole single-throw) switches exhibit a low minimum insertion loss of 0.66 dB (1.17 dB) at 85 GHz (84 GHz) with an extremely high corresponding isolation of 29.2 dB (24.5 dB). Even under extremely low DC-power consumption conditions of 0.95 mW (0.8 mW), the switches demonstrated impressive isolations of 23.7 dB (20.7 dB). Excellent mm-wave performance is also achieved with the 94 GHz SPDT (single-pole double-throw) switch. An insertion loss as low as 1.4 dB in transmit mode and 1.8 dB at 96 GHz in receive mode is obtained. A very high isolation value greater than 40 dB is observed. Furtherm...
Recent advances in the area of nitride-based wide-bandgap semiconductor technology allowed demons... more Recent advances in the area of nitride-based wide-bandgap semiconductor technology allowed demonstration of new generation devices with high power capability. Discrete GaNbased HFETs with 10W of output power at X-band have been recently demonstrated [1]. At the same time, electron transport in III-V nitrides is expected to have some common features with GaAsand InP-based materials. Thus, studies of fundamental properties in GaN indicate that this material also exhibits Negative Differential Resistance (NDR) and as a result, electrons exposed to high electric field experience negative differential mobility. However, the threshold field for NDR in GaN appears to be as much as 40 times higher than in GaAs ( FTH=150KV/cm vs. 3.5KV/cm) [2].
RF performance and improved DC characteristics were observed for GaN-based HEMTs using epitaxial ... more RF performance and improved DC characteristics were observed for GaN-based HEMTs using epitaxial layers grown on silicon via the SIGANTIC™ growth technique. The AlGaN/GaN HEMTs employed optical gate lithography (Lg = 1 µm) in the two-finger pi configuration. Measured devices exhibited good DC performance, with maximum transconductance and current densities of 110 mS/mm and 470 mA/mm respectively. A special technique based on current injection was used for performance evaluation and drain-to-source breakdown voltages VDS BD ~ 25 V – 35 V were observed. Microwave characteristics for these devices were also promising, where high current gain and maximum power gain frequencies of 5.9 GHz and 12 GHz, respectively.
This work addresses the scalability of power performance of AlGaN/GaN MODFETs with large gate per... more This work addresses the scalability of power performance of AlGaN/GaN MODFETs with large gate periphery, as necessary for microwave power devices. High-frequency largesignal characteristics of AlGaN/GaN MODFETs have been studied for devices with gate widths from 0.2 to 1 mm. 1-dB gain compression occurred at input power levels varying from-1 to +10dBm as the gate width increased, while gain remained almost constant at ~17dB. Output power density was maximum (1.3W/mm) for devices with 0.6mm gates and maximum output power (29.9dBm) occurred in devices with 1mm gates, while power-added-efficiency remained almost constant at ~30%. I. INTRODUCTION AlGaN/GaN heterojunction FETs grown by RF-assisted MBE have a high potential for highpower electronics as previously reported by the authors [1]. A record output power density of 3W/mm at 18GHz and 5.3W/mm at 10GHz [2] was recently obtained using AlGaN/GaN MODFETs. The DC and small-signal highfrequency performance of Al 0.3 Ga 0.7 N/GaN MODFETs...
Monolithic Integrated Circuit (MMIC) attenuators were realized for the first time. The MMICs empl... more Monolithic Integrated Circuit (MMIC) attenuators were realized for the first time. The MMICs employed AlGaN/GaN HEMTs fabricated by optical contact lithography (Lg=1µm) with high current gain (fT) and maximum power gain (fMAX) cutoff frequencies of 17 and 24GHz, respectively. The MMIC attenuators employing three 100µm-wide AlGaN/GaN HEMTs in π-configuration had minimum insertion of 4dB, high dynamic range (>30dB), and broadband operation (up to 18GHz). On-wafer power characterization at 8GHz confirmed successful operation of the GaN-based attenuator MMICs at power density exceeding 15W/mm. I.
— The design, fabrication, and experimental characteristics of InGaAs PIN diodes are presented fo... more — The design, fabrication, and experimental characteristics of InGaAs PIN diodes are presented for InP-based W-band monolithic integrated switches. The diodes with 10µm-diameter were used and showed a breakdown voltage of 17 V, a turnon voltage of 0.36 V, and a switching cutoff frequency of 6.3 THz. The monolithic integrated switches employed microstrip transmission lines and backside via holes for low-inductance signal grounding. A radial stub-based design was used for on-chip biasing, and the high-frequency characteristics of the switches were verified by on-wafer W-band testing. The SPST PIN monolithic switch demonstrated 25 dB isolation, 1.3 dB insertion loss, and 0.8 dB reflection loss at 83 GHz. I.
The DC and high frequency performance of AlGaN/GaN Heterojunction Bipolar Transistors (HBTs) is a... more The DC and high frequency performance of AlGaN/GaN Heterojunction Bipolar Transistors (HBTs) is analyzed using an enhanced drift-di€usion model and GaN/AlGaN material parameters, which were previously veri®ed by modeling experimental device characteristics. The emitter±base diode turn-on voltage is as high as 2.7 V while the collector and base ideality factors are 1.16 and 1.46 respectively. A DC current gain of b=15 is found at a collector current density of 2.5 kA/cm 2 and the gain is maintained at this value up to 4.1 kA/cm 2. The devices show a small o€set voltage of 0.5 V. A forward breakdown voltage BVCEO of 70 V is found for designs with collector doping of 5 10 16 cm �3. The current gain varied from 22 to 6 when the base doping was increased from 5 10 17 to 2 10 18 cm �3. At the same time, the maximum oscillation frequency fMAX increased from 3 to 6 GHz. A severe degradation of the current gain, fT, and fMAX was observed for HBT designs with a base thickness wider than 1000 ...
The GaN material parameters relevant to the negative di€erential resistance (NDR) devices are dis... more The GaN material parameters relevant to the negative di€erential resistance (NDR) devices are discussed, and their physical models based on the theoretical predictions and experimental device characteristics are introduced. Gunn diode design criteria were applied to design the GaN NDR diodes. A higher electrical strength of the GaN allowed operation with higher doping ( 1017 cm�3) and at a higher bias (90 V for a 3 µm thick diode). The transient hydrodynamic simulations were used to carry out the harmonic power analysis of the GaN NDR diode oscillators in order to evaluate their large-signal microwave characteristics. The GaAs Gunn diode oscillators were also simulated for a comparison and verification purposes. The dependence of the oscillation frequency and output power on the GaN NDR diode design and operating conditions are reported. It was found that, due to the higher electron velocities and reduced time constants, GaN NDR diodes o€ered twice the frequency capability of the Ga...
The frequency and power capability of GaN-based Gunn diodes is evaluated using transient hydrodyn... more The frequency and power capability of GaN-based Gunn diodes is evaluated using transient hydrodynamic simulations. GaN Gunn oscillators with 2µm-thick GaN Gunn diodes are predicted to have fundamental frequency of 148-162GHz and power density of>10 5 W/cm 2. Due to their high frequency and power characteristics, applications of these devices are envisaged for THz signal generation.
⎯ InP-based InGaAs PIN millimeterwave diodes were used to design and fabricate monolithic integra... more ⎯ InP-based InGaAs PIN millimeterwave diodes were used to design and fabricate monolithic integrated transmit-receive switches for W-band automotive applications. Coplanarwaveguide InGaAs PIN diode technology with reduced parasitics was employed for fabricating MMICs and yielded switches with high isolation and low insertion loss as shown by the performance of W-band single-pole double-throw switches. 77GHz SPDT switches demonstrated less than 1.35dB insertion loss, more than 43dB input-to-output isolation, and more than 30dB output-to-output crosstalk. W-band on-wafer large-signal characterization revealed no degradation of performance when the input power was increased to the maximum available level of +11dBm. I.
III-V Nitride Based MISFETs have been studied using AIN/GaN heterostructures grown by MOCVD at th... more III-V Nitride Based MISFETs have been studied using AIN/GaN heterostructures grown by MOCVD at the University of Michigan. MIS structures fabricated on such materials showed very low interface state density Dit values of -lx1011cm-2eV-1. The maximum drain current of AIN/GaN MISFETs made on these materials was greater than 700mA/mm, while drain-source breakdown was 30 V and drain-gate breakdown was 40V. Devices with a gate length of 2(j.m exhibited a peak transconductance of 136mS/mm at VGS=1V, which exceeds previously reported results.
Wide bandgap III-V nitride semiconductors are excellent candidates for high power applications an... more Wide bandgap III-V nitride semiconductors are excellent candidates for high power applications and superior power performance of AlGaN/GaN MODFETs has been reported recently [1]. Circuits designed for power applications such as power amplifiers, oscillators and mixers, operate under large-signal conditions and their performance can deviate significantly from small-signal predicted characteristics in case of frequency dependent device properties. It is consequently very important to understand and if possible control and suppress such dispersion effects. The low frequency output resistance (RDS) and transconductance (gm) dispersion characteristics of GaAs MESFETs [2]-[3] and GaAs as well as InP-based MODFETs [4]-[5] have been addressed by various groups. However, the dispersion characteristics of AlGaN/GaN MODFETs are not well understood at this point and significant interest exists in this area in order to explain dispersion between DC predicted and high–frequency measured power cha...
This paper demonstrates the design of high-isolation millimeter-wave monolithic integrated switch... more This paper demonstrates the design of high-isolation millimeter-wave monolithic integrated switches using MOCVD-grown InGaAs/InP PIN diodes as switching devices. W-band single-pole single-throw switch using double shunt diode topology allowed significant improvement of isolation while keeping insertion loss low. The SPST switch used two InGaAs PIN diodes and demonstrated better than 35dB isolation and 1.8dB insertion loss at 92GHz. A comparative analysis of single and double diode switch characteristics is treated together with the design and fabrication details. The power handling capability of the switches is also discussed.
GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing... more GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing Gunn design criteria applicable to this material system. Numerical simulations were used to carry out large-signal analysis of the GaN NDR diode oscillators in order to evaluate their potential for THz signal generation. It was found that, due to the higher electron velocity and reduced time constants involved in the diode operation, GaN NDR diodes offer significantly higher frequency and power capability than conventional GaAs Gunn diodes. Based on the performed analysis, THz signal generation using GaN-based NDR diodes was predicted. GaN NDR layer structures were grown by MOCVD. The fabrication technology and characterization techniques used for GaN NDR diode oscillators are presented.
GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing... more GaN-based Negative Differential Resistance (NDR) diode oscillators have been studied by employing Gunn design criteria applicable to this material system. Numerical simulations were used to carry out large-signal analysis of the GaN NDR diode oscillators in order to evaluate their potential for THz signal generation. It was found that, due to the higher electron velocity and reduced time constants involved in the diode operation, GaN NDR diodes offer significantly higher frequency and power capability than conventional GaAs Gunn diodes. Based on the performed analysis, THz signal generation using GaN-based NDR diodes was predicted. GaN NDR layer structures were grown by MOCVD. The fabrication technology and characterization techniques used for GaN NDR diode oscillators are presented.
We report on the measured performance of monolithic integrated mm-wave switching circuits which o... more We report on the measured performance of monolithic integrated mm-wave switching circuits which operate at Ka-Band. V-Band and W-Band as well as on a technology for multi-functional MMICs. The coplanar switches are using high-performance InGaAs PIN diodes as active switching elements. The focus of the illustrated measurement results is on the characteristics of the W-Band switches. The SPST (single-pole single-throw) switches exhibit a low minimum insertion loss of 0.66 dB (1.17 dB) at 85 GHz (84 GHz) with an extremely high corresponding isolation of 29.2 dB (24.5 dB). Even under extremely low DC-power consumption conditions of 0.95 mW (0.8 mW), the switches demonstrated impressive isolations of 23.7 dB (20.7 dB). Excellent mm-wave performance is also achieved with the 94 GHz SPDT (single-pole double-throw) switch. An insertion loss as low as 1.4 dB in transmit mode and 1.8 dB at 96 GHz in receive mode is obtained. A very high isolation value greater than 40 dB is observed. Furtherm...
Recent advances in the area of nitride-based wide-bandgap semiconductor technology allowed demons... more Recent advances in the area of nitride-based wide-bandgap semiconductor technology allowed demonstration of new generation devices with high power capability. Discrete GaNbased HFETs with 10W of output power at X-band have been recently demonstrated [1]. At the same time, electron transport in III-V nitrides is expected to have some common features with GaAsand InP-based materials. Thus, studies of fundamental properties in GaN indicate that this material also exhibits Negative Differential Resistance (NDR) and as a result, electrons exposed to high electric field experience negative differential mobility. However, the threshold field for NDR in GaN appears to be as much as 40 times higher than in GaAs ( FTH=150KV/cm vs. 3.5KV/cm) [2].
RF performance and improved DC characteristics were observed for GaN-based HEMTs using epitaxial ... more RF performance and improved DC characteristics were observed for GaN-based HEMTs using epitaxial layers grown on silicon via the SIGANTIC™ growth technique. The AlGaN/GaN HEMTs employed optical gate lithography (Lg = 1 µm) in the two-finger pi configuration. Measured devices exhibited good DC performance, with maximum transconductance and current densities of 110 mS/mm and 470 mA/mm respectively. A special technique based on current injection was used for performance evaluation and drain-to-source breakdown voltages VDS BD ~ 25 V – 35 V were observed. Microwave characteristics for these devices were also promising, where high current gain and maximum power gain frequencies of 5.9 GHz and 12 GHz, respectively.
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Papers by Egor Alekseev