High-density InGaN nanodots grown on pretreated GaN surfaces

Abstract

High-density InGaN nanodots are successfully grown on pretreated GaN surfaces. The GaN surfaces were covered by SiO2 layers firstly, and then the SiO2 layers were removed before the growth of InGaN on the GaN. After this process, the growth of InGaN on the GaN surfaces changed to a three-dimensional mode. However, on the GaN surface without the SiO2 treatment, the growth of InGaN maintained a two-dimensional growth mode as usual. The InGaN nanodots are 26to68nm in diameter, 3.6–15nm in height, and up to 9×1010cm−2 in density, which can be controlled by growth duration and substrate temperature. Comparing with the InGaN thin film grown on untreated GaN surface with the same growth conditions, the InGaN nanodots showed stronger photoluminescence in longer wavelength range at room temperature. The formation mechanism of the nanodots is described based on the GaN surface states changed by SiO2 coverage. This approach enables fabrication of dense and controllable InGaN nanodots.

In1−xGaxN@ZnO: a rationally designed and quantum dot integrated material for water splitting and solar harvesting applications

“…Similar emission features were observed for all InGaN@ZnO compositions with two sharp features at 420 and 440 nm and a shoulder at 480 nm, and these features are assigned to InGaN. 42 As the new emission features appear at higher λ than the ZnO band edge emission, the formation of new bands are suggested to be just above the VB. Indeed, extended visible light absorption up to 700 nm fully supports the broadening of VB in InGaN@ZnO.…”

Template-nonlithographic nanopatterning for site control growth of InGaN nanodots

“…The three-dimensional strain relaxation in nanodots allows more In atoms to be incorporated in the lattice and thus, it accounts for the redshifted PL peak from InGaN nanodots ͑with higher In composition͒ compared to the InGaN thin film. Higher In incorporation and redshifted PL peak in InGaN nanodots compared with InGaN thin film were also reported by Chen et al 20 To further investigate the optical properties of InGaN nanodots, temperature-dependent PL experiments were performed. The PL spectra for InGaN nanodots are shown in Fig.…”

Growth and Optical Properties of Highly Uniform and Periodic InGaN Nanostructures

“…The nanodot morphology was investigated by using an FEI Sirion 200 field emission scanning electron microscope. The micro-PL measurements were carried out by the excitation of a He-Cd cw laser (k ex = 25 nm) at a temperature ranging from 77 to 300 K. Random InGaN nanodots grown on a SiO 2 -treated GaN surface were used as reference sample (details have been described elsewhere [29]). …”

“…In fact, the present sample grown by NSAE has a lateral size deviation of 6 %, while the random nanodots exhibit a much larger size deviation of 30 %. [29] Nevertheless, the FWHM of the ordered InGaN nanodots is not as small as expected considering such high size uniformity, probably owing to the nonuniform distribution of the In composition induced by the selective growth. Figure 3 shows typical PL spectra from 60 nm InGaN nanodot arrays under different pumping levels of 0.01I 0 , 0.1I 0 , 0.8I 0 , and I 0 at 77 K, where the highest excitation power density I 0 is around 1.2 × 10 3 W cm -2 .…”

“…[28] In a previous report, we have described the formation of InGaN nanodots by using SiO 2 to supply Si as the antisurfactant. [29] However, those were random nanodots. We first reported InGaN nanodots and nanorings grown on patterned GaN surfaces by NSAE, in which the growth template is patterned by nanopatterns in the porous aluminum oxide.…”