Overcoming the Miscibility Gap of GaN/InN in MBE Growth of Cubic In_xGa_1–xN

Abstract

The lack of internal polarization fields in cubic group-III nitrides makes them promising arsenic-free contenders for next-generation high-performance electronic and optoelectronic applications. In particular, cubic In x Ga 1−x N semiconductor alloys promise band gap tuning across and beyond the visible spectrum, from the near-ultraviolet to the near-infrared. However, realization across the complete composition range has been deemed impossible due to a miscibility gap corresponding to the amber spectral range. In this study, we use plasma-assisted molecular beam epitaxy (PAMBE) to fabricate cubic In x Ga 1−x N films on c-GaN/AlN/3C-SiC/Si template substrates that overcome this challenge by careful adjustment of the growth conditions, conclusively closing the miscibility gap. X-ray diffraction reveals the composition, phase purity, and strain properties of the In x Ga 1−x N films. Scanning transmission electron microscopy reveals a CuPt-type ordering on the atomistic scale in highly alloyed films with x(In) ≈ 0.5. Layers with much lower and much higher indium content exhibit statistical distributions of the cations Ga and In. Notably, this CuPt-type ordering results in a spectrally narrower emission compared to that of statistically disordered zincblende materials. The emission energies of the films range from 3.24 to 0.69 eV and feature a quadratic bowing parameter of b = 2.4 eV. In contrast, the LO-like phonon modes that are observed by Raman spectroscopy exhibit a one-mode behavior and shift linearly from c-GaN to c-InN.

Efficiency of InN/InGaN/GaN Intermediate-Band Solar Cell under the Effects of Hydrostatic Pressure, In-Compositions, Built-in-Electric Field, Confinement, and Thickness

“…This deterioration can be attributed to the presence of spontaneous and piezoelectric polarizations, coupled with dislocation effects due to the rise in lattice mismatching between the layers. These challenges stem from the complexities encountered in achieving high-quality InGaN-based layers with indium compositions exceeding 50%, collectively contributing to the degradation of the device's performance [35]. In Figure 7a, we delve into the variation in photovoltaic efficiency (η) for a specific pressure value at P = 10 GPa and l 1 (0) = 2l 2 = 2 a * b across four distinct values of GaN layer thickness; η shows an ascent to a maximum point followed by a descent for all considered compositions.…”

“…InGaN-based layers with indium compositions exceeding 50%, collectively contributing to the degradation of the device's performance [35]. In Figure 7a, we delve into the variation in photovoltaic efficiency (𝜂 ) for a specific pressure value at 𝑃 = 10 GPa and 𝑙 (0) = 2𝑙 = 2 𝑎 * across four distinct values of GaN layer thickness; 𝜂 shows an ascent to a maximum followed by a descent for all considered compositions.…”

“…Temperature dependence affects carrier dynamics, and achieving optical gain in InGaN/GaN QWs is crucial for their use in semiconductor lasers [33,34]. Ongoing research actively addresses challenges such as the "green gap" and material degradation, focusing on new designs and manufacturing techniques to enhance the efficiency and reliability of InGaN/GaN QWs in practical optoelectronic devices [35].…”

Enhancing Emission via Radiative Lifetime Manipulation in Ultrathin InGaN/GaN Quantum Wells: The Effects of Simultaneous Electric and Magnetic Fields, Thickness, and Impurity

“…For an indium composition of 10% (δ = 0.1) and an experimentally obtained bowing parameter of 2.3 (b = 2.3) [38], the energy band gap of InGaN becomes…”