High-speed InP/Ga0.47In0.53As superlattice avalanche photodiodes with very low background doping grown by continuous trichloride vapor-phase epitaxy

Abstract

Trichloride vapor-phase epitaxy has been employed in a single chamber reactor to achieve the continuous (noninterrupted) growth of n−InP/n−In0.53Ga0.47As/InP superlattice structures for avalanche photodetector applications. Very low background doping has been achieved in both the InP (n≊1×1014 cm−3) and the superlattice layers (n=1×1015 cm−3). We report the details of the epitaxial crystal growth as well as analysis of the structures by secondary ion mass spectrometry and transmission electron microscopy. Avalanche photodiodes have been fabricated by Zn diffusion in the InP layer and mesa etching. The devices exhibit an intrinsic response time (full width at half maximum) of 66 ps at λ=1.5 μm which is the shortest so far achieved in superlattice photodetectors. Dark currents of 50 nA at unity gain, multiplication factors of 6, and breakdown voltages exceeding −120 V have been measured.