Drain current DLTS analysis of recoverable and permanent degradation effects in AlGaAs/GaAs and AlGaAs/InGaAs HEMT'S

We present a detailed study of drain current DLTS spectra performed on as-received and failed AlGaAs/GaAs and AlGaAs/InGaAs HEMT's of four differ ent suppliers submitted to hot-electron tests. We demonstrate that a remarkable correlation exists between DLTS features and permanent and recoverable degradation effects. In particular, different behaviours have been found: (i) recoverable effects seems to be correlated with modulation of charge trapped on DX and ME6 centers. (ii) permanent degradation consisting in a decrease in Id and V-T is due to negative charge trapping and is associated with a large increase of a peak having Ea=1.22 eV in the DLTS spectra of failed devices; (iii) development of traps in the gate-to-drain access region induces a permanent increase in drain parasitic resistance Rd and decrease in Id, and is correlated with the growth of a ''hole-like'' peak in DLTS spectra measured after hot-electron tests. Copyright (C) 1996 Elsevier Science Ltd