Photoluminescence Imaging of Semiconductor Structures Grown Using Selective Area Epitaxy

Abstract

Selective Area Growth (SAG) is a technique developed for cost savings in semiconductor manufacturing, allowing for local area growth manipulation. In this work, SAG was accomplished by using a lithographic direct-write laser system that creates silica (SiO2) masks on the surface of a III-V semiconductor substrate. The III-V semiconductor substrate used was a semi-insulating GaAs (SI-GaAs) wafer of (100) orientation. A lattice-matched InGaP/GaAs/InGaP heterostructure was grown using Molecular Beam Epitaxy (MBE). This heterostructure has a theoretical photoluminescence (PL) emission peak of approximately 875 nm and exhibited strong PL. A micro-photoluminescence (μ-PL) apparatus was successfully built and consists of a HeNe laser of 633 nm emission wavelength as the excitation source. The μ-PL apparatus captured the emission spectrum of the sample with a spatial resolution of approximately 6 μm and a peak wavelength around 878 nm. The images are scans of various area sizes, ranging from 0.0413-6.25 mm2. The images showed that the silica structures are non-growth sites due to the absence of PL. The images also showed a reduction in PL intensity in areas near silica structures. This is hypothesized to be due to variations in the InGaP layers that ultimately affect growth quality and carrier confinement. No change in PL wavelength was observed in the growth regions, as would be expected for a binary system grown by MBE. The PL imaging of selectively grown heterostructure materials enables further process development for integration of semiconductors with multiple bandgaps on a chip for fiber optic transmission.