Transient current spectroscopy and frequency dispersion studies of low temperature GaAs and Al0.3Ga0.7As metal-insulator-semiconductor diodes

Abstract

Low temperature (LT)-grown GaAs and Al0.3Ga0.7 As metal-insulator-n+-GaAs (MIN) diodes have been fabricated and their electrical properties analyzed. Studies were carried out to evaluate the interfacial quality of the LT layer and the underlying n+-GaAs layer using transient current spectroscopy (TCS) and capacitance-frequency (C-f) characterization. TCS studies on LT-GaAs revealed a high concentration of a continuum of states and a dominant electron trap with an activation energy of 0.52 eV. In LT-Al0.3Ga0.7As, a shallow trap at 0.36 eV and two deep level traps at 0.85 eV and 1.12 eV were observed. Frequency dispersion was observed to be less for LT-GaAs samples with an AlAs barrier layer than without an AlAs barrier layer. However, LT-Al0.3Ga0.7As MIN diodes displayed a smaller frequency dispersion than LT-GaAs MIN diodes. Upon further investigation into MISFET devices, it was found that LT-Al0.3Ga0.7As MISFET devices had better transconductance frequency dispersion characteristics than LT-GaAs MISFET devices did.