GaN:-Mg grown by MOVPE: Structural properties and their effect on the electronic and optical behavior

Abstract

The effect of Mg δ-doping on the structural, electrical and optical properties of GaN grown via metalorganic vapor phase epitaxy has been studied using transmission electron microscopy, secondary ion mass spectroscopy, atomic force microscopy, x-ray diffraction, Hall effect measurements and photoluminescence. For an average Mg concentration above 2.14 × 10 19 cm −3 , phase segregation occurs, as indicated by the presence of Mg-rich pyramidal inversion domains in the layers. We show that δ-doping promotes, in comparison to Mg continuous doping, the suppression of extended defects on the samples surface and improves significantly the morphology of the epilayers. Conversely, we can not confirm the reduction in the threading dislocation density -as a result of δ-doping -reported by other authors. In the phase separation regime, the hole concentration is reduced with increasing Mg concentration, due to self-compensation mechanisms. Below the solubility limit of Mg into GaN at our growth conditions, potential fluctuations result in a red-shift of the emission energy of the free-to-bound transition.

Performance Improvement of Nitride-Based Light-Emitting Diode With a Thin Mg-Delta-Doped Hole Injection Layer

“…Based on the Gaussian fittings, the dominant BL emission lines of the uniformly-doped and delta-doped sample were 2.86 eV and 2.89 eV, respectively. The blue shift of BL band peak in delta-doped sample is ascribed to the increase of coulomb energy resulting from the reduction of average distance between the donor-acceptor pair in the thin Mg-delta-doped region [41]. It can also be observed that the Mg-delta-doped sample shows additional violet luminescence (VL) emission bands peaked at 3.41 eV and 3.27 eV.…”

“…4. The increment of Mg ions concentration in the thin Mg-delta-doped region decreases the Fermi level and raises the local conduction band [41]. The delta-doped region with higher potential may serve as an electron blocking layer.…”

Computational high throughput screening of inorganic cation based halide perovskites for perovskite only tandem solar cells

“…We started with 45 perovskite materials, combining 3 inorganic cations, 5 metals, and 3 halogens, as shown in figure 1. The geometry of the perovskites are optimised in all the 3 phases (cubic, orthorhombic, and tetragonal) using the PBE exchange-correlation functional [43] in order to get the structures with the lowest potential energy. The initial lattice parameters of the perovskites are given in supplementary information is available online at stacks.iop.org/MRX/7/055502/mmedia.…”

“…Inorganic materials are known to have higher stability than the organic materials, especially at higher temperatures [29][30][31]. This aspect has been exploited quite well experimentally, in which the organic cation has been replaced by the inorganic Cs + cation that resulted in a rapid decrease in instability problems, thereby promising a relatively higher intrinsic or thermodynamic stability against decomposition to binary halide products [32][33][34][35][36][37][38][39][40][41][42][43][44]. However, theoretical investigation towards this pressing issue is still limited [11][12][13][14][15][16][17][18][19].…”

Analysis and modeling of the experimentally observed anomalous mobility properties of periodically Si-delta-doped GaN layers

“…Mg-delta-doped GaN claimed that this method not only effectively improve the material quality, but also increases the hole concentration by the reduction of Mg activation energy and self compensation effect. [4][5][6] In this way, a hole concentration near 10 18 cm À3 could be obtained. Nevertheless, few works have been published on the growth or properties of n-type Si-delta-doped GaN, 7,8 among which the mobility behavior has not yet been concerned about.…”