Lateral diffusion in 2-micron InGaAs/GaAsSb superlattice planar diodes using atomic layer deposition of ZnO

TL;DR

This paper presents a novel planar InGaAs/GaAsSb superlattice diode fabrication method using atomic layer deposition of ZnO, achieving low dark current and promising quantum efficiency for gas sensing applications.

Contribution

It introduces a new planar diode fabrication technique with optimized diffusion processes, improving device performance and manufacturability over traditional mesa-structure diodes.

Findings

Diffusion depth of 50 nm with lateral diffusion of 18-30 microns.

Room temperature dark current of 1E-6 A at -2V for 30-micron diode.

Quantum efficiency of 11.11% at 2 microns illumination.

Abstract

Avalanche photodiodes used for greenhouse gas sensing often use a mesa-structure that suffers from high surface leakage currents and edge breakdown. In this paper, we report 2-micron InGaAs/GaAsSb superlattice (SL) based planar PIN diodes to eliminate the challenges posed by conventional mesa diodes. An alternate way to fabricate planar diodes using atomic layer deposited ZnO was explored and the effect of the diffusion process on the superlattice was studied using X-ray diffraction. The optimum diffusion conditions were then used to make planar PIN diodes. The diffused Zn concentration was measured to be approximately 1E20 cm-3 with a diffusion depth of 50 nm and a lateral diffusion ranging between 18 microns to 30 microns. A background doping of 5.8 x 1E14 cm-3 for the UID layer was determined by analyzing the capacitance-voltage measurements of the superlattice PIN diodes. The room temperature dark current for a device with a designed diameter of 30 microns is 1E-6 A at -2V. The quantum efficiency of the diode with a designed diameter of 200 microns was obtained to be 11.11% at 2-micron illumination. Further optimization of this diffusion process may lead to a rapid, manufacturable, and cost-effective method of developing planar diodes.