A comparative study of surface passivation on AlGaN/GaN HEMTs

Abstract Using a Si 3 N 4 layer as passivation layer, effects of surface passivation on device performances have been investigated. After passivation, devices exhibited better pinch-off characteristics and lower gate leakage current. For a device with a gate-length of 0.25 μm, the I dss increased from 791 to 812.2 mA/mm and the peak extrinsic transconductance increased from 207.2 to 220.9 mS/mm. The f T and f MAX values decreased from 53 and 102.5 to 45.9 and 90.5 GHz, respectively, due to the increase of parasitic capacitances. Microwave noise measurements showed that devices exhibited 0.2–0.25 dB increase in minimum noise figure (NF min ) after passivation.

[1]  N. Hara,et al.  Surface-charge controlled AlGaN/GaN-power HFET without current collapse and gm dispersion , 2001, International Electron Devices Meeting. Technical Digest (Cat. No.01CH37224).

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

[3]  J. Zolper,et al.  Wide bandgap semiconductor microwave technologies: from promise to practice , 1999, International Electron Devices Meeting 1999. Technical Digest (Cat. No.99CH36318).

[4]  S. Keller,et al.  High breakdown GaN HEMT with overlapping gate structure , 2000, IEEE Electron Device Letters.

[5]  Y.-F. Wu,et al.  High Al-content AlGaN/GaN HEMTs on SiC substrates with very high power performance , 1999, International Electron Devices Meeting 1999. Technical Digest (Cat. No.99CH36318).

[6]  Ilesanmi Adesida,et al.  AlGaN/GaN HEMTs on SiC with over 100 GHz f/sub T/ and low microwave noise , 2001 .

[7]  Y.-F. Wu,et al.  GaN microwave electronics , 1997, 1997 Topical Symposium on Millimeter Waves. Proceedings (Cat. No.97TH8274).

[8]  R. J. Shul,et al.  GAN : PROCESSING, DEFECTS, AND DEVICES , 1999 .

[9]  J. Palmour,et al.  High power demonstration at 10 GHz with GaN-AlGaN HEMT hybrid amplifiers , 2000, 58th DRC. Device Research Conference. Conference Digest (Cat. No.00TH8526).

[10]  P. Janke,et al.  GaN/AlGaN high electron mobility transistors with f τ of 110 GHz , 2000 .

[11]  Michael S. Shur,et al.  GaN based transistors for high power applications , 1998 .

[12]  B. Ridley,et al.  Passivation of AlGaN/GaN heterostructures with silicon nitride for insulated gate transistors , 2000, Proceedings 2000 IEEE/ Cornell Conference on High Performance Devices (Cat. No.00CH37122).