Electrical and Thermal Property of Si/GaAs Heterojunction Formed by Ultra-Thin Oxide Interfacial Layer

TL;DR

This study demonstrates Si/GaAs heterojunctions with ultra-thin Al2O3 layers, revealing optimized electrical and thermal properties, small conduction band discontinuity, and reliable diode behavior, advancing heterojunction integration.

Contribution

It introduces a novel method using ultra-thin Al2O3 layers to improve Si/GaAs heterojunctions, with detailed analysis of band offsets, defect densities, and thermal transport.

Findings

Optimal UO thickness (~1 nm) enhances carrier transport.

UO layer facilitates phonon and electron tunneling.

Heterojunction diodes exhibit low ideality factor and rectification.

Abstract

We have successfully demonstrated Si/GaAs p-n heterostructures using Al2O3 ultra-thin oxide interfacial layers. The band diagram and band offsets were investigated using X-ray photoelectron spectroscopy and confirm a small discontinuity in the conduction band (0.03 eV) at the interface. The interface defect density (Dit) values of the heterointerface with different ultra-thin oxide (UO) thicknesses ranged from 0.35 nm to 3.5 nm and were also characterized based on a metal-oxide-semiconductor capacitor (MOSCAP) structure using a capacitance-voltage measurement. The results revealed that a thin UO interfacial layer (around 1 nm) maximizes carrier transport property due to better surface passivation and efficient tunneling properties. Thermal property investigation also shows that the Al2O3 UO interfacial layer offers a good tunneling layer but also facilitates phonon transport across the interface. Finally, the electrical characterization of Si/GaAs heterojunction p-n diodes confirms reliable rectifying behavior with an extremely low ideality factor; thus, heterogeneous integration using the UO approach offers a robust way to create more types of heterojunctions between dissimilar semiconductors.