GaAs–Ga<i>x</i>Al1−<i>x</i>As Heterostructure Injection Lasers which Exhibit Low Thresholds at Room Temperature

TLDR

The study describes the electrical and optical properties of GaAs–GaxAl1−xAs injection lasers fabricated by solution epitaxy. The lasers consist of a three‑layer structure (n‑GaAs, thin p‑GaAs, and p‑GaxAl1−xAs) and are fabricated as Fabry‑Perot diodes with ~400 µm cavities, yielding threshold currents of ~10 kA/cm² at 300 K, while fully internally reflected modes achieve ~6–7 kA/cm². The threshold current is minimized when the p‑GaAs layer is ~2 µm thick, shows weak temperature dependence below a maximum temperature TM, and reaches as low as 8600 A/cm² at 300 K—lower than previously reported—attributed mainly to carrier confinement, with hole injection influencing the Jth minimum and temperature behavior.

Abstract

The electrical and optical properties of GaAs–GaxAl1−xAs injection lasers produced by solution epitaxy are described. These lasers are composed of three layers, n-GaAs, a thin p-GaAs layer, and a p-GaxAl1−xAs layer. In these lasers, the threshold current Jth is a strong function of the width of the p-GaAs layer d, being optimum where d is about 2 μ. The temperature dependence of Jth is comparatively small below some maximum temperature TM, above which it increases very rapidly. The values of Jth obtained near room temperature for these lasers are lower than have previously been reported for injection lasers. Fabry-Perot-type diodes with cavities of about 400 μ may be reproducibly prepared with Jth (300°K) about 10 000 A/cm2. The lowest Jth (300°K) observed for one of these units was 8600 A/cm2. Units with fully internally reflected modes can be reproducibly prepared with Jth (300°K) ≈6000–7000 A/cm2. The low Jth (300°K) of these lasers is attributed primarily to carrier confinement, although improved optical confinement and reduced absorption losses may also play a role. The behavior of Jth at TM and the minimum in Jth as a function d are attributed to hole injection.