ABSTRACT
Rui Jia, Seiya Kasai and Hideki Hasegawa Research Center for Integrated Quantum Electronics and Graduate School of Information Science and Technology, Hokkaido University, Japan.
Abstract. Investigation of gate control and current-voltage (/- V) characteristics of nanometer scale Schottky electrodes is in an attempt to clarify the possible effects of surface states. HEMT devices having nanometer-sized Schottky gate showed a gate controllability so that the effective gate length was extended, as well as Schottky gate’s anomalous I-V characteristics different from the prediction of thermionic emission theory. QWRTrs having an additional side gate exhibited large side-gating effect that was much larger than that by side gate depletion with anomalous side gate leakage current. The origin of obtained gate control anomalies is understood by the high-density surface state charging in gate peripheries that produces strong electric field and induces excess surface state charging by carrier injection from the gate. 1
1. Introduction Nanometer-scale Schottky gates are used for control of electron transport in advanced III-V nanodevices including nanometer-gate HEMTs for quantum wire transistors (QWRTrs) and single electron transistors (SETs). In these devices, the gate length becomes smaller than the depletion layer depth with increased field near the gate periphery, making gate control characteristics more sensitive to condition of the free surface in gate peripheries involving anomalous gate leakage current. For example, we have shown that I-V characteristics of nanometer-scale GaAs and InP Schottky diodes are very much modified by Fermi level pinning [1]. More recently, we have found strong side-gating phenomenon in AlGaAs/GaAs QWRTrs, suggesting involvement of surface states [2]. However, no systematic understanding of surface state effects in III-V devices controlled by the nanometer-scale Schottky gates has been reported so far in the literature.
