Transient Leakage Current Technique for MIS HEMT (Al2O3/AlGaN/GaN) Dielectric Semiconductor Interface Property Characterization

摘要

The semiconductor industry owes its success critically to surface,and interface states properties control. New characterization techniques are increasingly in demand with the advent of complex,hetero junction device structures,and ferroelectric semiconductors with polarization induced charge pairs. For instance,the nature of the charges or traps on or near the surface of the barrier layer of GaN HEMT structure has eluded detection for the past decade. The irreversible removal of polarization induced,surface mobile holes was proposed to be the root cause of high power GaN transistor current collapse,and the presence of these positive charges was recently verified [1] [2]. However,conventional test methods have failed to provide key information on surface holes density. This letter describes an unconventional procedure to measure the dielectric semiconductor interface electronics properties of an Al2O3/AlGaN/GaN MIS HEMT structure,in which carriers are supplied by polarization induced,electron-hole charge pairs. The nulls in I-V plot of MIS device leakage current are found to be good indicators of static potential,and the nature of the mobile charges at the dielectric-semiconductor interface. Both the surface mobile hole,and transistor channel 2-DEG sheet charge density can be assessed by means of this highly unconventional method.