GaAs/Ge/Si epitaxial substrates: Development and characteristics

Yury Buzynin,Vladimir Shengurov,Boris Zvonkov,Dmitry Pavlov,Michail Drozdov,Pavel Yunin,Sergey Denisov,Nikolay Baidus,Alexander Buzynin

doi:10.1063/1.4974498

Abstract

We developed high quality 2-inch GaAs/Ge/Si (100) epitaxial substrates, which may be used instead of GaAs monolithic substrates for fabrication of solar cells, photodetectors, LEDs, lasers, etc. A 200–300 nm Ge buffer layer was grown on Si substrates using the HW-CVD technique at 300°C, a tantalum strip heated to 1400°C was used as the “hotwire”. The MOCVD method was used to grow a 1 μ GaAs layer on a Ge buffer. The TDD in the GaAs layers did not exceed (1–2)∙105 cm-2 and the surface RMS roughness value was under 1 nm.

Highlights

Si substrates compared to GaAs ones are lighter, strong, and cheaper and have a better capacity for conducting heat
This is due to a number of fundamental problems, the most important of which are an appreciable mismatch of the lattice parameters and thermal expansion coefficients of Si and GaAs, as well as the growth peculiarities of a polar GaAs layer on a nonpolar Si substrate
We studied the grown heterostructures using a variety of methods including optical, electron scanning (SEM) and transmission (TEM) and atomic-force (AFM) microscopy, secondary ions mass spectroscopy (SIMS), X-ray diffractometry (XRD) and photoluminescence (PL)

Summary

INTRODUCTION

Si substrates compared to GaAs ones are lighter, strong, and cheaper and have a better capacity for conducting heat This makes Si substrates as valuable alternative to GaAs ones, if we learn to use them for growing device quality GaAs epitaxial layers for use in fabrication of microwave devices, solar cells, photodetectors, LEDs, lasers, etc. Such a replacement is a necessary step towards the monolithic integration of III-V-based optoelectronic devices and Si chips.. This technique made it possible to fabricate a variety of GaAs/Ge/GeSi/Si based minority carrier devices, such as solar cells, LEDs and injection lasers. We report the data on structure, morphology, photoluminescence properties and the results of SIMS analysis of the GaAs/Ge/Si heterostructures

EXPERIMENTAL SECTION

RESULTS AND DISCUSSION

CONCLUSIONS