Prof Yulin Chen

Abstract:

The electrical properties of a type of semiconductor heterostructure fabricated by depositing zinc oxide film on a silicon substrate are investigated. The I - V , I - T curves, and deep level transient spectra are measured. From these results, we acquire the information of the characteristics of the junction, and compute some energy levels of the samples.

Abstract:

Extensive capacitance-voltage (C-V) and conductance-voltage (G-V) measurements have been performed on MIS devices on p-type GaSb at 77 K using an anodically grown oxide as the insulating layer. The C-V characteristics have been measured from 250 Hz to 800 kHz. The high-frequency C-V data and the G-V analysis are in good agreement and show that there is a high density of surface states (∼10¹³ cm^-2 eV^-1) which limits the movement of the surface potential to a region of approximately 1/4 of the bandgap. Hence neither accumulation nor inversion can be obtained.

Abstract:

A new class of insulating and passivating layers on gallium antimonide has been prepared by means of an electrochemical process. In previous work we used this new process of fabrication of passivating and insulating layers for gating devices made from GaSb/InAs/GaSb nanostructures (Chen Y et al 1994 Superlatt. Microstruct. 15 41 and Chen Y 1995 PhD Thesis Hertford College, Oxford, UK). In this publication we describe the effects of the electrochemical process leading to an improvement of the photoluminescence (PL) after the growth of the passivating layer on GaSb. The PL measurements on <100>, <111A> and <111B> GaSb substrates and on GaSb epilayers grown by MOVPE on GaAs indicate significant improvement of the PL intensity even after 12 months. Similar results have been observed on InGaSb/GaSb superlattice structures.