Temperature-controlled epitaxy of InxGa1-xN alloys and their band gap bowing

Abstract

InxGa1-xN alloys (0 ≤ x ≤ 1) have been grown on GaN/sapphire templates by molecular beam epitaxy. Growth temperature controlled epitaxy was proposed to modulate the In composition so that each InxGa1-xN layer was grown at a temperature as high as possible and thus their crystalline quality was improved. The bandgap energies of the InxGa1-xN alloys have been precisely evaluated by optical transmission spectroscopy, where the effect of residual strain and electron concentration (the Burstein-Moss effect) on the bandgap energy shift has been considered. Finally, a bowing parameter of ∼1.9 ± 0.1 eV has been obtained by the well fitting In-composition dependent bandgap energy.

Vacancy-type defects in InxGa1–xN alloys probed using a monoenergetic positron beam

“…The observed increase in the FWHM values of XRD and PL intensity can be associated with the alloy disorder or compositional inhomogeneity caused by the increase in the strain energy. 10 The S values for In x Ga 1-x N (x ¼ 0, 0.5, and 1) were calculated from Doppler broadening spectra simulated by the PAW method. A relationship between the S value and x was then obtained from the fitting of these values using a firstdegree polynomial function, and the results are shown in Fig.…”

“…The growth method and the optical properties of samples prepared by this method are described elsewhere. 10 The Ga-polar GaN(4.5 lm)/sapphire templates were prepared using metal organic chemical vapor deposition (MOCVD). During the growth of In x Ga 1-x N, the substrate temperature was controlled to modulate the In composition, where the samples with different In compositions were grown at their highest temperature (500 $ 650 C).…”

“…[2][3][4] and better understanding of the growth mechanism for In-rich In x Ga 1-x N, however, the quality of epitaxial In x Ga 1-x N films has rapidly improved. [5][6][7][8][9][10] The band gap energy of In x Ga 1-x N can cover the polar spectrum, which offers a high degree of freedom in the design of tandem solar cell structures. Group III-nitrides show very strong absorption at the band edge, high radiation resistance, and high thermal conductivity.…”

Intersubband Transition in GaN/InGaN Multiple Quantum Wells

“…As mentioned above, in order to grow high quality InGaN layers, the growth temperature controlled epitaxy is used here 21 , where the InGaN layer is grown at its maximum temperature of 620 °C at metal-rich condition, which leads to a flat surface and is helpful for improving the interface sharpness. Figure 2(a) shows the typical surface morphologies of the grown samples, which are free of cracks because the GaN/InGaN MQWs exhibit compressive strain when growing on the GaN:Si templates.…”

“…The self-consistent Schrödinger-Poisson equations assumed periodic potential conditions and charge neutrality conditions. In the calculation, the band gap was chosen to be 3.4 eV (0.65 eV) for GaN (InN), and the band gap bowing parameter for InGaN was set as 1.9 eV 21 . The ratio of conduction band offset to the total band offset was set as 65%.…”