Phase separation suppression in InGaN epitaxial layers due to biaxial strain

Universität Paderborn, Paderborn, North Rhine-Westphalia, Germany
Applied Physics Letters (Impact Factor: 3.3). 03/2002; 80(5):769 - 771. DOI: 10.1063/1.1436270
Source: IEEE Xplore


Phase separation suppression due to external biaxial strain is observed in In x Ga 1-x N alloy layers by Raman scattering spectroscopy. The effect is taking place in thin epitaxial layers pseudomorphically grown by molecular-beam epitaxy on unstrained GaN(001) buffers. Ab initio calculations carried out for the alloy free energy predict and Raman measurements confirm that biaxial strain suppress the formation of phase-separated In-rich quantum dots in the In x Ga 1-x N layers. Since quantum dots are effective radiative recombination centers in InGaN, we conclude that strain quenches an important channel of light emission in optoelectronic devices based on pseudobinary group-III nitride semiconductors. © 2002 American Institute of Physics.

Download full-text


Available from: Lara K. Teles
  • [Show abstract] [Hide abstract]
    ABSTRACT: Uniform InGaN nanodots were successfully grown on SiO2 pretreated GaN surface. It was found that the InGaN nanodots were 20 nm in diameter and 5 nm in height, approximately. After the growth of two periods of InGaN/GaN quantum wells on the surface of InGaN nanodots, nanodot structure still formed in the InGaN well layer caused by the enhanced phase separation phenomenon. Dual-color emissions with different behavior were observed from photoluminescence (PL) spectrum of InGaN nanodots hybrid with InGaN/GaN quantum wells. A significant blueshift and a linewidth broadening were measured for the low-energy peak as the increase of PL excitation power, while a slight blueshift and a linewidth narrowing occurred for the high-energy peak. Accordingly, these two peaks were assigned to be from the In-rich nanodots and quantized state transition from the InGaN/GaN quantum wells with indium content, respectively.
    No preview · Article · Nov 2012 · Applied Physics A
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work we analyze the luminescence emissions from selected isolated GaN/InGaN quantum wells comparing measured and theoretical photoluminescence (PL) spectra. The calculations are performed within the k · p method by means of an 8 × 8 Kane Hamiltonian, generalized to treat different materials. Strain effects due to the large lattice mismatch between InN and GaN are taken into account. From the direct comparison with experimental results, we found evidence for transitions involving confined levels which, besides those related to quantum dots, may be ascribed to the first electron–heavy-hole transition in the quantum wells. Since the studies of optical properties of quantum wells based on cubic nitrides are at an early stage, the results reported here will provide guidelines for the interpretation of forthcoming experiments.
    No preview · Article · Mar 2002 · physica status solidi (a)
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present first-principles calculations of the thermodynamic and electronic properties of the zinc-blende ternary InxGa1-xN, InxAl1-xN, BxGa1-xN, and BxAl1-xN alloys. They are based on a generalized quasi-chemical approximation and a pseudopotential-plane-wave method. T-x phase diagrams for the alloys are obtained. We show that due to the large difference in interatomic distances between the binary compounds a significant phase miscibility gap for the alloys is found. In particular for the InxGa1-xN alloy, we show also experimental results obtained from X-ray and resonant Raman scattering measurements, which indicate the presence of an In-rich phase with x[approximate]0.8. For the boron-containing alloy layers we found a very high value for the critical temperature for miscibility, \textasciitilde9000 K, providing an explanation for the difficulties encountered to grow these materials with higher boron content. The influence of a biaxial strain on phase diagrams, energy gaps and gap bowing of these alloys is also discussed.
    Full-text · Article · Mar 2002 · Physica E Low-dimensional Systems and Nanostructures
Show more