Planar-doped n-type InAlAs/InGaAs MODFETs on InP(311)A substratesby molecular beam epitaxy

N-type doping of silicon in InAlAs/InGaAs/InP modulation-doped field effect transistor (MODFET) structures grown by molecular beam epitaxy (MBE) for the (311)A orientation has been achieved by using the planar-doping technique. An electron mobility as high as 50000 cm² V-s with a sheet carrier concentration of 1.9×10¹²/cm² at 77 K is reported. MODFETs with 1.2-μm gate length exhibit an extrinsic transconductance of 400 mS/mm and a maximum drain current of 485 mA/mm. The results are comparable to those of MODFETs grown on (100) InP substrates. The results point to the possibility of making p-n multi layer structures with all-silicon doping     

AlGaN-GaN HEMTs on Si with power density performance of 1.9 W/mm at 10 GHz

AlGaN-GaN high electron mobility transistors (HEMTs) on silicon substrate are fabricated. The device with a gate length of 0.3-/spl mu/m and a total gate periphery of 300 /spl mu/m, exhibits a maximum drain current density of 925 mA/mm at V/sub GS/=0 V and V/sub DS/=5 V with an extrinsic transconductance (g/sub m/) of about 250 mS/mm. At 10 GHz, an output power density of 1.9 W/mm associated to a power-added efficiency of 18% and a linear gain of 16 dB are achieved at a drain bias of 30 V. To our knowledge, these power results represent the highest output power density ever reported at this frequency on GaN HEMT grown on silicon substrates.     

AlGaN/GaN HEMTs on (111) silicon substrates

AlGaN/GaN HEMTs on silicon substrates have been fabricated and their static and small-signal RF characteristics investigated. The AlGaN/GaN material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current of 0.91 A/mm, a good pinchoff and a peak extrinsic transconductance of 122 mS/mm. A unity current gain frequency of 12.5 GHz and f_max/f_T=0.83 were obtained. The highest saturation current reported so far, static output characteristics of up to 20 V and breakdown voltage at pinchoff higher than 40 V demonstrate that the devices are capable of handling ~16 W/mm static heat dissipation     

A normally off GaN n-MOSFET with Schottky-barrier source and drain on a Si-auto-doped p-GaN/Si

We have fabricated an enhancement-mode n-channel Schottky-barrier-MOSFET (SB-MOSFET) for the first time on a high mobility p-type GaN film grown on silicon substrate. The metal contacts were formed by depositing Al for source/drain contact and Au for gate contact, respectively. Fabricated SB-MOSFET exhibited a threshold voltage of 1.65 V, and a maximum transconductance(g/sub m/) of 1.6 mS/mm at V/sub DS/=5V, which belongs to one of the highest value in GaN MOSFET. The maximum drain current was higher than 3 mA/mm and the off-state drain current was as low as 3 nA/mm.     

AlGaN/GaN HEMTs on silicon substrates with fT of 32/20GHz and fmax of 27/22 GHz for 0.5/0.7 μm gate length

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current density of 0.53 to 0.68 A/mm and a peak extrinsic transconductance of 110 mS/mm. A unity gain frequency of 20 and 32 GHz and a maximum frequency of oscillation of 22 and 27 GHz are obtained for devices with a gate length of 0.7 and 0.5 μm, respectively. These values are the highest reported so far on AlGaN/GaN/Si HEMTs and are comparable to those known for devices using sapphire and SiC substrates     

High microwave and noise performance of 0.17-/spl mu/m AlGaN-GaN HEMTs on high-resistivity silicon substrates

AlGaN-GaN high-electron mobility transistors (HEMTs) based on high-resistivity silicon substrate with a 0.17-/spl mu/m T-shape gate length are fabricated. The device exhibits a high drain current density of 550 mA/mm at V/sub GS/=1 V and V/sub DS/=10 V with an intrinsic transconductance (g/sub m/) of 215 mS/mm. A unity current gain cutoff frequency (f/sub t/) of 46 GHz and a maximum oscillation frequency (f/sub max/) of 92 GHz are measured at V/sub DS/=10 V and I/sub DS/=171 mA/mm. The radio-frequency microwave noise performance of the device is obtained at 10 GHz for different drain currents. At V/sub DS/=10 V and I/sub DS/=92 mA/mm, the device exhibits a minimum-noise figure (NF/sub min/) of 1.1 dB and an associated gain (G/sub ass/) of 12 dB. To our knowledge, these results are the best f/sub t/, f/sub max/ and microwave noise performance ever reported on GaN HEMT grown on Silicon substrate.     

AlGaN/GaN HEMTs on SiC with f/sub T/ of over 120 GHz

AlGaN/GaN high electron mobility transistors (HEMTs) grown on semi-insulating SiC substrates with a 0.12 /spl mu/m gate length have been fabricated. These 0.12-/spl mu/m gate-length devices exhibited maximum drain current density as high as 1.23 A/mm and peak extrinsic transconductance of 314 mS/mm. The threshold voltage was -5.2 V. A unity current gain cutoff frequency (f/sub T/) of 121 GHz and maximum frequency of oscillation (f/sub max/) of 162 GHz were measured on these devices. These f/sub T/ and f/sub max/ values are the highest ever reported values for GaN-based HEMTs.     

High-temperature performance of AlGaN/GaN HFETs on SiC substrates

The performance results AlGaN-GaN Heterostructure Field Effect Transistors (HFETs) grown on SiC substrates are reported. The maximum transconductance of these devices was 142 mS/mm and the source-drain current was as high as 0.95 A/mm. The maximum dissipated DC power at room temperature was 0.6 MW/cm², which is more than three times higher than that in similar devices grown on sapphire. This high thermal breakdown threshold was achieved primarily due to the effective heat sink through the SiC substrate. These devices demonstrated stable performance at elevated temperatures up to 250°C. The source-drain current saturation was observed up to 300°C. The leakage current in the below threshold regime was temperature-activated with an activation energy of 0.38 eV     

Large-signal performance of deep submicrometer AlGaN/AlN/GaNHEMTs with a field-modulating plate

This is the first time that the microwave performance of a 0.1-/spl mu/m gate in a silicon nitride window opening, with a field-modulating plate on an AlGaN/AlN/GaN heterojunction structure, is reported. The material structure was grown by organometallic vapor phase epitaxy on SiC substrates with an averaged channel sheet resistance of 313.5 ohms/square. Approximately 80-nm-thick plasma-enhanced chemical vapor deposition silicon nitride is used as the dielectric between gate metal extension and semiconductor surface. Transistors of a total gate width of 250 /spl mu/m and a 0.1 /spl mu/m gate footprint, with a 0.36 /spl mu/m long overhang on top of the silicon nitride, can be operated at a drain bias of 40-V high. Output power density of 9.5 W/mm, with 36% power-added efficiency in class AB regime, was demonstrated at 10 GHz in a continuous wave power measurement.     

2.1 A/mm current density AlGaN/GaN HEMT

The electrical performance of high current density AlGaN/GaN HEMTs is reported. 2 /spl times/ 75 /spl mu/m /spl times/ 0.7 /spl mu/m devices grown on sapphire substrates showed current densities up to 2.1 A/mm under 200 ns pulse condition. RF power measurements at 8 GHz and V/sub DS/=15 V exhibited a saturated output power of 3.66 W/mm with a 47.8% peak PAE.     

MOCVD-grown AlInAs/GaInAs MODFET with drain currents higher than 1.3 mA/mm

Very high-density and high-mobility AlInAs/GaInAs modulation-doped heterostructures have been successfully grown by low-pressure MOCVD. FETs, having gate-lengths of 0.25 mu m, fabricated from these heterostructures show transconductances as high as 700 mS/mm, and drain saturation currents in excess of 1.3 mA/mm at V/sub gs/=0 V. This current density is among the highest yet reported for FETs grown by any technique. The extracted current-gain cutoff frequency is 78 GHz.<>     

Microwave performance of 0.4 mu m gate metamorphic In/sub 0.29/Al/sub 0.71/As/In/sub 0.3/Ga/sub 0.7/As HEMT on GaAs substrate

MBE grown metamorphic In/sub 0.29/Al/sub 0.71/As/In/sub 0.3/Ga/sub 0.7/As/GaAs high electron mobility transistors (HEMTs) have been successfully fabricated. A 0.4 mu m triangular gate device showed transconductance as high as 700 mS/mm at a current density of 230 mA/mm. The measured f/sub T/ was 45 GHz and f/sub max/ was 115 GHz. These high values are, to the authors knowledge, the first reported for submicrometre metamorphic InAlAs/InGaAs/GaAs HEMTs with an indium content of 30%.<>     

Thin film pseudomorphicAlAs/In0.53Ga0.47As/InAs resonant tunnellingdiodes integrated onto Si substrates

We report high peak-to-valley current ratio (PVR) resonant tunneling diodes (RTDs) bonded to silicon. Pseudomorphic AlAs/In_0.53Ga_0.47As/InAs resonant tunneling diode structures grown on semi-insulating InP with peak-to-valley current ratios as high as 30 at 300 K have been separated from the growth substrate and bonded to silicon substrates coated with Si₃N ₄, forming thin film devices. In addition, thin film multiple stack RTD structures have been bonded to silicon substrates. The I-V characteristics of both the single and multi-stacked thin film RTD's exhibit no signs of degradation after bonding to the host substrate. These results are the first successful demonstration of InP based electronics bonded to a silicon host substrate and enable the integration of RTDs with conventional silicon circuitry     

12 W/mm AlGaN-GaN HFETs on silicon substrates

Al/sub 0.26/Ga/sub 0.74/N-GaN heterojunction field-effect transistors were grown by metal-organic chemical vapor deposition on high-resistivity 100-mm Si (111) substrates. Van der Pauw sheet resistance of the two-dimensional electron gas was 300 /spl Omega//square with a standard deviation of 10 /spl Omega//square. Maximum drain current density of /spl sim/1 A/mm was achieved with a three-terminal breakdown voltage of /spl sim/200 V. The cutoff frequency and maximum frequency of oscillation were 18 and 31 GHz, respectively, for 0.7-/spl mu/m gate-length devices. When biased at 50 V, a 2.14-GHz continuous wave power density of 12 W/mm was achieved with associated large-signal gain of 15.3 dB and a power-added efficiency of 52.7%. This is the highest power density ever reported from a GaN-based device grown on a silicon substrate, and is competitive with the best results obtained from conventional device designs on any substrate.     

AlGaN-GaN HEMTs on patterned silicon (111) substrate

We report the AlGaN-GaN high-electron mobility transistors (HEMTs) grown and fabricated on patterned silicon (111) substrates. A crack-free AlGaN-GaN HEMT heterostructure was grown on top of rectangular silicon ridges patterned on the silicon substrate. Fabrication of HEMT on the ridges was demonstrated using a polyimide planarization process. Maximum drain current density of 1.05 A/mm and peak transconductance of 150 mS/mm were achieved with 1.0 /spl mu/m gate-length. The current gain cutoff frequency and maximum frequency of oscillation were 9.7 and 20.5 GHz, respectively, for the 1 /spl mu/m /spl times/ 300 /spl mu/m devices.     

0.23 mu m gate length MODFETs on InAlAs/InGaAs/InP heterostructure grown by MOVPE

Modulation-doped field effect transistors (MODFETs) with 0.23 mu m gate lengths have been fabricated on an InAlAs/InGaAs/InP heterostructure grown by metal organic vapour phase epitaxy (MOVPE/MOCVD). Extrinsic DC transconductance as high as 800 mS/mm, and unity current gain cutoff frequency f/sub t/ of over 120 GHz at room temperature have been achieved. These g/sub m/ and f/sub t/ values compare favourably with the best devices of similar gate length grown by molecular-beam epitaxy (MBE) and are the highest values reported for any device grown by MOVPE.<>     

DC and microwave performance of high-current AlGaN/GaNheterostructure field effect transistors grown on p-type SiC substrates

The fabrication and characterization of high performance AlGaN/GaN heterostructure field effect transistors (HFETs) grown on p-type SiC substrates are reported for the first time. The HFETs were fabricated with gate lengths of 0.25, 0.5, and 1 μm. These devices exhibited simultaneously high drain currents, high extrinsic transconductances, and excellent frequency response. The 0.25-μm gate-length devices produced a peak drain current of 1.43 A/mm, a transconductance of 229 mS/mm, a unity current-gain cutoff frequency of 53 GHz, and a maximum frequency of oscillation of 58 GHz. The unity current-gain cutoff frequency also exhibited little degradation as the drain-source bias was swept up to 20 V. These results represent a significant improvement over similar HFETs grown on sapphire substrates and are attributed to the higher thermal conductivity and reduced lattice mismatch associated with SiC substrates     

DC and RF performance of GaAs MESFET fabricated on silicon substrate using epitaxial lift-off technique

GaAs MESFETs have been fabricated on a silicon substrate using a molecular beam epitaxy grown film detached from its growth substrate and attached on a silicon substrate covered with a dielectric. The device processing is done on the silicon substrate. The MESFETs exhibit I/sub DSS/=130 mA/mm, g/sub m/=135 mS/mm and for 1.3 mu m gate length unity current gain cut-off frequency f/sub T/ of 12 GHz. Excellent device isolation with subpicoampere leakage currents is obtained.<>     

GaAs/AlGaAs power heterobipolar transistor fabricated on silicon substrate

A GaAs/AlGaAs power HBT was fabricated on a silicon substrate, where the thermal conductance is reduced by a factor of 2.8 compared with that on bulk GaAs. Due to the newly developed monolithically grown ballast resistor in the emitter region, the experimentally fabricated device has shown the highest collector current of over 2.5 A for a device with an active device area of 0.14 mm/sup 2/.<>     

Millimeter-wave high-power 0.25-/spl mu/m gate-length AlGaN/GaN HEMTs on SiC substrates

Reports on the CW power performance at 20 and 30 GHz of 0.25 /spl mu/m /spl times/ 100 /spl mu/m AlGaN/GaN high electron mobility transistors (HEMTs) grown by MOCVD on semi-insulating SiC substrates. The devices exhibited current density of 1300 mA/mm, peak dc extrinsic transconductance of 275 mS/mm, unity current gain cutoff (f/sub T/) of 65 GHz, and maximum frequency of oscillation (f/sub max/) of 110 GHz. Saturated output power at 20 GHz was 6.4 W/mm with 16% power added efficiency (PAE), and output power at 1-dB compression at 30 GHz was 4.0 W/mm with 20% PAE. This is the highest power reported for 0.25-/spl mu/m gate-length devices at 20 GHz, and the 30 GHz results represent the highest frequency power data published to date on GaN-based devices.