Title :
Thermal stability of MISFET with low-temp molecular-beam epitaxy-grown GaAs and Al0.3Ga0.7As gate ins
Author :
Rao, Rapeta V V V J ; Chong, T.C. ; Tan, L.S. ; Lau, W.S.
Author_Institution :
Centre for Wireless Commun., Nat. Univ. of Singapore, Singapore
fDate :
6/1/2000 12:00:00 AM
Abstract :
GaAs and Al0.3Ga0.7As epilayers grown at LT by MBE were used as insulators in the fabrication of MISFET devices. Parametric changes were used to evaluate the thermal stability of MISFET, to identify failure mechanisms and validate the reliability of these devices. The LT-Al0.3Ga0.7As MISFET showed superior thermal stability. The degradation in the performance of MISFET with 1000 Å thick LT-GaAs gate insulator was worse than those of the MESFET. On the other hand, MISFET with 250 Å thick LT-GaAs gate insulators exhibited stable characteristics with thermal stressing, LF (low frequency) noise studies on the TLM structures of MISFET layers exhibited 1/f noise in the LT-Al0.3Ga0.7As samples and 250 Å LT-GaAs samples; whereas the 1000 Å thick LT-GaAs samples exhibited 1/f3/2 noise, which was attributed to: (i) the thermal noise generated at the interface of the insulator, and (ii) the active layer due to the outdiffused metallic arsenic. Reverse gate-drain current degradation experiments were carried out at 120°C, 160°C, 200°C, and 240°C. Transconductance frequency dispersion studies were carried out before and after thermal stress on these MISFET. The transconductance of MISFET with 1000 Å LT-GaAs gate insulators was degraded by 40% at 100 kHz after thermal stress. The rest of the samples exhibited stable characteristics. These results indicate that composition changes had occurred at the interface in thicker LT-GaAs MISFET structures. Thinner LT-layers are ideal for achieving higher transconductance and better thermal stability without sacrificing the power capability of MISFET
Keywords :
1/f noise; III-V semiconductors; MISFET; Schottky gate field effect transistors; aluminium compounds; failure analysis; gallium arsenide; life testing; molecular beam epitaxial growth; semiconductor device reliability; semiconductor epitaxial layers; thermal noise; thermal stability; 0.95 eV; 1/f noise; 1000 A; 120 to 240 C; 250 A; Al0.3Ga0.7As; Al0.3Ga0.7As epilayer; GaAs; GaAs epilayer; MESFET; MISFET; activation energy; active layer; composition changes; device reliability; failure analysis; failure mechanisms; gate insulators; insulators; low frequency noise; low-temp molecular-beam epitaxy; low-temperature MBE growth; metal insulator semiconductor field-effect transistor; outdiffused metallic arsenic; reverse gate-drain current degradation; thermal noise; thermal stability; thermal stress; thermal stressing; transconductance frequency dispersion; Active noise reduction; Frequency; Insulation; Low-frequency noise; MISFETs; Noise generators; Thermal degradation; Thermal stability; Thermal stresses; Transconductance;
Journal_Title :
Reliability, IEEE Transactions on