Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the short and mid-wavelength infrared regions

TL;DR

This study investigates nonpolar GaN/Al(Ga)N heterostructures grown on bulk GaN, demonstrating room-temperature intersubband absorption in the infrared range, with m-plane structures showing superior optical and structural properties.

Contribution

It provides a comparative analysis of nonpolar and polar GaN/Al(Ga)N quantum wells, highlighting the advantages of m-plane structures for infrared intersubband optoelectronic applications.

Findings

m-plane structures exhibit best mosaicity and surface quality

Room-temperature intersubband absorption from 1.5 to 2.9 μm in m-plane structures

Tunable intersubband absorption from 4.0 to 5.8 μm in designed samples

Abstract

This paper assesses nonpolar m- and a-plane GaN/Al(Ga)N multi-quantum-wells grown on bulk GaN for intersubband optoelectronics in the short- and mid-wavelength infrared ranges. The characterization results are compared to those for reference samples grown on the polar c-plane, and are verified by self-consistent Schr\"odinger-Poisson calculations. The best results in terms of mosaicity, surface roughness, photoluminescence linewidth and intensity, as well as intersubband absorption are obtained from m-plane structures, which display room-temperature intersubband absorption in the range from 1.5 to 2.9 um. Based on these results, a series of m-plane GaN/AlGaN multi-quantum-wells were designed to determine the accessible spectral range in the mid-infrared. These samples exhibit tunable room-temperature intersubband absorption from 4.0 to 5.8 um, the long-wavelength limit being set by the absorption associated with the second order of the Reststrahlen band in the GaN substrates.