Advances in Light Emission from Group-IV Alloys via Lattice Engineering and n-Type Doping Based on Custom-Designed Chemistries

Abstract

Intrinsic and n-type Ge1–ySny alloys with y = 0.003–0.11 have been grown on Ge-buffered Si via reactions of Ge3H8 and SnD4 hydrides using UHV-CVD techniques. The films exhibit large thicknesses (t > 600 nm), low dislocation densities (107/cm2), planar surfaces (AFM RMS ≈ 2 for intrinsic films) and mostly relaxed microstructures, making them suitable for subsequent characterization of the emission properties using photoluminescence (PL) spectroscopy. The PL spectra are acquired at room temperature and show tunable and distinct direct and indirect gap emission peaks versus composition. The peak intensity in a given sample is found to increase by exposing the layers to hydrogen plasma, indicating that surface passivation plays an important role in eliminating carrier recombination traps. The PL intensity is further increased by n-type doping with P/As atoms at levels 0.8–7 × 1019 cm–3using P(GeH3)3, P(SiH3)3, and As(SiH3)3 precursors, indicating that desirable direct gap conditions can be approached even at ...