Direct observation of contact potential distributions of wafer-bonded p-GaAs-GaN and p-GaAs-Si by scanning Kelvin probe force microscopy

摘要

Electrical properties of the wafer bonding p-GaAs-GaN, p-GaAs-Si and p-GaAs/ITO//ITO-Si are investigated systematically by scanning Kelvin probe force microscopy (KPFM), capacitance-voltage (C-V) and current-voltage (I-V) measurements. By using KPFM, the contact potential distributions and contact barrier differences of these bonding heterojunctions with Schottky-like characteristics or ohmic feature have been obtained. The contact barrier differences measured by KPFM match well with those measured by C-V. These barriers indicate the thicker interface layer has a larger barrier height, which could contain more interface states. The I-V curve of the heterostructure with the smaller contact barrier difference is shown as an Ohmic contact feature. In contrast, the I-V curve of the junction with the larger contact barrier difference shows a Schottky contact behavior with a larger turn-on voltage. These behaviors indicate that the electrical conductivity of the bonding sample depends on the bonding interface layer significantly.