Broadband light emission from GaAsP and GaInP islands grown on silicon nanotip wafer via nanoheteroepitaxy

Abstract

We present the monolithic integration of GaAsxP1−x and GaxIn1−xP islands, selectively grown on a Si(001) nanotip wafer using gas-source molecular-beam epitaxy via a nanoheteroepitaxy approach. Optimal growth temperatures balancing selectivity and compositional control are 520–580 °C for GaAsP and 500–510 °C for GaInP. By adjusting the group III and V fluxes, island luminescence is tuned across a broad spectral range from 1.5 to 2.1 eV. High-resolution x-ray diffraction measurements on ensembles exceeding one million islands confirm that both GaAsP and GaInP islands are relaxed, while broad diffraction linewidths point to alloy fluctuations. Scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy reveals compositional variations of up to 6% among the GaAsP islands, with nearly uniform composition within individual islands. In the case of GaInP, indium-rich regions are observed within single islands, with up to 11% variation across the ensemble. These compositional variations result in broadened or multiple luminescence peaks. Despite challenges in achieving full uniformity, this work demonstrates an alternative pathway for the monolithic integration of scalable III–V infrared-to-visible light emitters and detectors on silicon, advancing the development of microscale light sources for the silicon platform.