Biaxial Strain Modulated Valence Band Engineering in III-V Digital Alloys

TL;DR

This paper investigates how biaxial strain influences valence band structure in III-V digital alloys, revealing methods to optimize hole transport and reduce noise in avalanche photodiodes through lattice engineering.

Contribution

It provides a detailed explanation of minigap formation using tight binding theory and demonstrates how substrate lattice constant adjustments can modulate band structure.

Findings

Decreasing substrate lattice constant increases minigap size and hole effective mass.

Lattice tuning reduces quantum tunneling and phonon scattering.

Band structure modifications are applicable to various III-V digital alloys.

Abstract

Some III-V digital alloy avalanche photodiodes exhibit low excess noise. These alloys have low hole ionization coefficients due to presence of small 'minigaps', enhanced effective mass and large separation between light-hole and split-off bands in the valence band. In this letter, an explanation for the formation of the minigaps using a tight binding picture is provided. Furthermore, we demonstrate that decreasing substrate lattice constant can increase the minigap size and mass in the transport direction. This leads to reduced quantum tunneling and phonon scattering of the holes. Finally, we illustrate the band structure modification with substrate lattice constant for other III-V digital alloys.