GaN nanowire (NW) arrays have been fabricated by the electrodeless photoelectrochemical (PEC) etching method for the first time. Under appropriate conditions, the etching process is just a dislocation-hunted process, in which the etching solution "digs down'' along the threading dislocations, resulting in the formation of GaN NWs by preferentially ...
Crack-free GaN epitaxial layer was obtained through inserting 80 nm graded AlGaN buffer layer between GaN epilayer and high temperature AlN buffer on 2-in Si(111) substrates by metal organic chemical vapor deposition. This paper investigated the influence of AlGaN buffer thickness on the structural properties of the GaN epilayer. It was confirmed f...
Molecular beam epitaxy growth of GaAs-based long-wavelength metamorphic InAs/InGaAs quantum dots (QDs) is investigated. With optimized multi-step-graded InGaAs metamorphic buffer layers and growth conditions, room temperature 1.46 mu m emission from InAs/In(0.15)Ga(0.85)As QDs is realized, and broad-area laser diodes are fabricated with a very low ...
Strain relaxation in large lattice-mismatched epitaxial films, such as Ge and III-V materials on Si, introduces high threading dislocation densities (TDDs). A thermodynamic model of TDD dependence on film thickness is developed. According to this model, the quasiequilibrium TDD of a given strain-relaxed film scales down with the inverse square of i...
Thick GaN films of high quality are directly grown on wet-etching patterned sapphire in a vertical hydride vapour phase epitaxy reactor. The optical and structural properties of GaN films are studied using scanning electronic microscopy and cathodoluminescence. Test results show that initial growth of hydride vapour phase epitaxy GaN occurs not onl...
A close relationship is found between the blue and yellow luminescence bands in n-type GaN films, which are grown without intentional acceptor doping. The intensity ratio of blue luminescence to yellow luminescence (I-BL/I-YL) decreases with the increase in edge dislocation densities as demonstrated by the (102) full width at half maximum of x-ray ...
A theory of scattering by charged dislocation lines in a quasitriangle potential well of AlxGa1-xN/GaN heterostructures is developed. The dependence of mobility on carrier sheet density and dislocation density is obtained. The results are compared with those obtained from a perfect two-dimensional electron gas and the reason for discrepancy is give...
The theoretical electron mobility limited by dislocation scattering of a two-dimensional electron gas confined near the interface of AlxGa1-xN/GaN heterostructures was calculated. Based on the model of treating dislocation as a charged line, an exponentially varied potential was adopted to calculate the mobility. The estimated mobility suggests tha...
Under identical preparation conditions, Au/GaN Schottky contacts were prepared on two kinds of GaN epilayers with significantly different background electron concentrations and mobility as well as yellow emission intensities. Current-voltage (I-V) and variable-frequency capacitance-voltage (C-V) characteristics show that the Schottky contacts on th...
The strain evolution of the GaN layer grown on a high-temperature AlN interlayer with GaN template by metal organic chemical vapor deposition is investigated. It is found that the layer is initially under compressive strain and then gradually relaxes and transforms to under tensile strain with increasing film thickness. The result of the in situ st...
