Band Structure and Quantum Confined Stark Effect in InN/GaN superlattices

Abstract

InN/GaN superlattices offer an important way of band gap engineering in the blue-green range of the spectrum. This approach represents a more controlled method than the band gap tuning in quantum well systems by application of InGaN alloys. The electronic structures of short-period wurtzite InN/GaN(0001) superlattices are investigated, and the variation of the band gap with the thicknesses of the well and the barrier is discussed. Superlattices of the form mInN/nGaN with n ≥ m are simulated using band structure calculations in the Local Density Approximation with a semiempirical correction for the gap error. The calculated band gap shows a strong decrease with the thickness (m) of the InN well. In superlattices containing a single layer of InN (m = 1) the band gap increases weakly with the GaN barrier thickness n, reaching a saturation value around 2 eV. In superlattices with n = m and n > 5 the band gap closes and the systems become “metallic”. These effects are related to the existence of the built-in electric fields that strongly influence valence- and conduction-band profiles and thus determine effective band gap and emission energies of the superlattices. Varying the widths of the quantum wells and barriers one may tune band gaps over a wide spectral range, which provides flexibility in band gap engineering.

Influence of strain and internal electric fields on band gaps in short period nitride based superlattices

“…2 the calculated band gaps for mInN/nGaN SLs for different numbers of well (m) and barrier (n) MLs are presented. Some of these results were already published and discussed [1,2]. We present them (with some new sets of SLs added) for comparison with the results obtained for GaN/AlN -in order to discuss similarities and differences.…”

“…In cases when the considered artificial short period SL structures have been successfully manufactured, we discuss their photoluminescence (PL) characteristics in the light of our ab-initio calculations. Some earlier studies of E g in nitride short period SLs have been carried out by us [1][2][3], Stampfl et al [4,5], Krukowski et al [6], and Miao et al [7].…”

“…Some of the mInN/nGaN SLs were already studied [1][2][3]. Calculations were performed for wurtzite mInN/nGaN(0001) SLs in a 'free-standing' [1] (F-S) geometry (all the lattice parameters fully relaxed) and a 'pseudomorphic' [2] (ps) configuration (lattice dimensions perpendicular to the growth direction matched to those of a substrate), and for three different growth directions (c-, a-, and m-orientations) [3].…”

“…Calculations were performed for wurtzite mInN/nGaN(0001) SLs in a 'free-standing' [1] (F-S) geometry (all the lattice parameters fully relaxed) and a 'pseudomorphic' [2] (ps) configuration (lattice dimensions perpendicular to the growth direction matched to those of a substrate), and for three different growth directions (c-, a-, and m-orientations) [3]. The electronic band structures were analysed in more detail including lattice relaxations, charge distributions and band profiles.…”

Study of the optical-electrical characteristics of In Ga1−N alloy with low in doping

“…Growth and study the properties of the alloy by experiment are expensive and rigor to the condition of experiment, lately, due to the development of computer technology, the theoretical simulation becomes a kind of important means, whether in the bulk, surface or heterojunction [9][10][11]. Wang Xiaoke studied the energy gap of Ga doped InN with the first-principles ultrasoft pseudopotential method [12], Dridi studied the electronic properties of GaN doped with In [13], Roberto Nunez-Gonzalez calculated the band structure of InGaN with different In concentration [14].…”