Growth mechanism of InGaN quantum dots during metalorganic vapor phase epitaxy

Abstract

Growth mechanism of InGaN quantum dots on GaN was studied during metalorganic vapor phase epitaxy in a temperature range of 600–750°C in a horizontal reactor. Atomic force microscopy and high resolution X-ray diffraction show that InGaN quantum dots on GaN are formed according to the Stranski–Krastanov growth mode. When growth temperature was varied between 600 and 750°C, a 2–3-dimensional growth transition was observed below 650°C due to the increase in indium content. While the layer thickness was varied, similar transitions were observed with critical thicknesses of ∼2.7nm and ∼4nm at growth temperatures of 625°C (In0.31Ga0.69N) and 675°C (In0.22Ga0.78N), respectively. InGaN quantum dots with a density of ∼1010cm−2, an average diameter of ∼40nm and average height of ∼4nm were obtained. Reciprocal space maps from the asymmetric (10–15) reflection show that all the InGaN samples are fully strained. Strong green emission at 534nm was observed from InGaN grown at 675°C.