MBE growth, characterization, and applications of indium arsenide/gallium phosphide heterojunctions

En-Hsing Samuel Chen, Purdue University

Abstract

InAs is an attractive semiconductor for application to high-speed electronic devices and optoelectronic devices in the infrared region. In recent times, there has been an increased interest in the epitaxial growth of InAs on commonly available substrate materials such as Si, GaAs, and InP. Recently, Chang et al. reported that by growing InAs directly on GaP by MBE, the epilayer strain relaxes via the formation of an array of pure edge-type (90°) dislocations at the heterointerface. The density of the threading dislocations was reported relatively low. In this thesis, we further examined the material, electrical and optical characteristics of nearly relaxed InAs/GaP heterojunctions. In spite of the large lattice mismatch (∼11%) and high density of 90° edge-type dislocations, the electrical characteristics were surprisingly good. The resulting I-V characteristics of both the isotype and anisotype junctions showed low leakage currents and high breakdown voltages in reverse bias and nearly ideal, Schottky-barrier like, forward bias characteristics with ideality factors of 1.1 or less. The InAs/GaP Schottky diodes also exhibit better device reliability than commonly used metal-semiconductor Schottky diodes. Internal photoemission of relaxed InAs/GaP heterejunctions, has also been studied. Both band-to-band and free-carrier transitions were observed in this heterostructure, and this result may lead to useful photodiodes. Finally, The material quality of the epitaxial InAs film has also been examined by X-ray and Hall measurement. Very high electron mobility has been achieved and this result demonstrates the possibility of using this InAs/GaP heterostructure as a template for the growth of small band gap structures using the InGaAs/InAlAs system.

Degree

Ph.D.

Advisors

Woodall, Purdue University.

Subject Area

Electrical engineering|Condensation

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