Fabrication and characterization of AlGaN/GaN High Electron Mobility Transistor

Abstract

As primary material for semiconductor fabrication field, Gallium nitride has attracted lots of interest of scientists and developers due to its unique and exceptional electrical properties such as high thermal conductivity, high electron mobility, high breakdown field, and mechanical and chemical endurance under harsh conditions. Since GaN has those superior electrical properties induced by its wide band gap energy compared to the conventional semiconductor materials, it would be applied to many different electronic applications. This dissertation describes the fabrication and characterization of high electron mobility transistor(HEMT) based on GaN wafer. The HEMTs consist of the schottky metal contact and ohmic contact on same direction of the wafer. A GaN layer has been deposited on the silicon wafer. Between gallium nitride layer and the silicon substrate there are different layers to buffer each layers. The ohmic contact will be connected by electron channel through the GaN layers where the two- dimensional electron gas channel (2DEG) is formed. Two dimensional electron gas channel would allow electron carriers to pass through without any intentional dopings, which makes costs less and reduced processing steps to fabricate. Fabricated HEMTs are characterized by measuring current-voltage curve (I-V) and capacitance-voltage curve (C-V), in order to verify HEMT’s electrical properties. Photocurrent-voltage curve measurement also has been carried out to investigate how the GaN would react to light illumination and how the electric current output could increase.