210-GHz InAlN/GaN HEMTs With Dielectric-Free Passivation

Lattice-matched depletion-mode InAlN/AlN/GaN high-electron mobility transistors (HEMTs) on a SiC substrate were fabricated, for the first time, with a dielectric-free passivation (DFP) process in which the device access region was treated by O2/Ar plasma. Similar to dielectric passivation using SiN and Al2O3, the plasma treatment can effectively shorten the gate-length extension. As a result, the current gain cutoff frequency fT of a 60-nm rectangular-gate HEMT increased from 125 to 210 GHz after the plasma DFP; this RF performance is among the highest reported fT for GaN-based HEMTs. The device showed a dc drain current density of 2.1 A/mm and a peak extrinsic transconductance of 487 mS/mm after DFP. The Lg-fTproduct of 12.6 GHz ·μm is among the highest reported for a gate-physical-length-to-barrier-thickness aspect ratio of 5.6. Small gate lag and drain lag are observed in pulsed I-V measurements with a 300-ns pulsewidth.

[1]  G. Snider,et al.  Enhancement-Mode InAIN/AIN/GaN HEMTs With 10―12 A/mm Leakage Current and 1012 ON/OFF Current Ratio , 2011 .

[2]  Patrick Fay,et al.  High-performance monolithically-integrated E/D mode InAlN/AlN/GaN HEMTs for mixed-signal applications , 2010, 2010 International Electron Devices Meeting.

[3]  I. Adesida,et al.  ALD AI/sub 2/O/sub 3/ passivated MBE-grown AIGaN/GaN HEMTs on 6H-SiC , 2007 .

[4]  Toshiaki Matsui,et al.  AlGaN/GaN Heterostructure Field-Effect Transistors on 4H-SiC Substrates with Current-Gain Cutoff Frequency of 190 GHz , 2008 .

[5]  Yu Cao,et al.  Threshold Voltage Control in Al 0.72 Ga 0.28 N/AlN/GaN HEMTs by Work-Function Engineering , 2010 .

[6]  U. Mishra,et al.  AlGaN/GaN HEMTs-an overview of device operation and applications , 2002, Proc. IEEE.

[7]  M. Singh,et al.  Device scaling physics and channel velocities in AIGaN/GaN HFETs: velocities and effective gate length , 2006, IEEE Transactions on Electron Devices.

[8]  A. Fung,et al.  220GHz fT and 400GHz fmax in 40-nm GaN DH-HEMTs with re-grown ohmic , 2010, 2010 International Electron Devices Meeting.

[9]  V. Miller,et al.  High-Power Ka-Band Performance of AlInN/GaN HEMT With 9.8-nm-Thin Barrier , 2010, IEEE Electron Device Letters.

[10]  Hideki Hasegawa,et al.  Mechanisms of current collapse and gate leakage currents in AlGaN/GaN heterostructure field effect transistors , 2003 .

[11]  Haifeng Sun,et al.  205-GHz (Al,In)N/GaN HEMTs , 2010, IEEE Electron Device Letters.

[12]  L. Eastman,et al.  The effect of surface passivation on the microwave characteristics of undoped AlGaN/GaN HEMTs , 2000, IEEE Electron Device Letters.

[13]  Hideki Hasegawa,et al.  Chemistry and electrical properties of surfaces of GaN and GaN/AlGaN heterostructures , 2001 .

[14]  Yu Cao,et al.  AlN/GaN Insulated-Gate HEMTs With 2.3 A/mm Output Current and 480 mS/mm Transconductance , 2008, IEEE Electron Device Letters.

[15]  Yu Cao,et al.  Threshold Voltage Control in $\hbox{Al}_{0.72} \hbox{Ga}_{0.28}\hbox{N/AlN/GaN}$ HEMTs by Work-Function Engineering , 2010, IEEE Electron Device Letters.

[16]  Xiang Gao,et al.  Gate-Recessed Enhancement-Mode InAlN/AlN/GaN HEMTs With 1.9-A/mm Drain Current Density and 800-mS/mm Transconductance , 2010, IEEE Electron Device Letters.

[17]  Toshiaki Matsui,et al.  Reduction in potential barrier height of AlGaN∕GaN heterostructures by SiN passivation , 2007 .

[18]  J. Chyi,et al.  Low-/spl kappa/ BCB passivation on AlGaN-GaN HEMT fabrication , 2004 .

[19]  D.S. Katzer,et al.  Improved reliability of AlGaN-GaN HEMTs using an NH/sub 3/ plasma treatment prior to SiN passivation , 2005, IEEE Electron Device Letters.

[20]  Tomas Palacios,et al.  Advanced gate technologies for state-of-the-art fT in AlGaN/GaN HEMTs , 2010, 2010 International Electron Devices Meeting.