Regularly arranged InGaN-based nanocolumns and related device technology

By use of Ti-mask selective area growth (SAG) technique by rf-MBE for Ga, various regularly arranged InGaN-based nanocolumn arrays with triangular-lattice arrays were grown on the same substrate; three-period InGaN/GaN MQWs were prepared at top regions of the nanocolumns. Change in the emission color from blue to red with increasing the nanocolumn diameter was observed for the samples. Here, the photoluminescence peak wavelength shifted monotonically from 513 nm to 622 nm. The beam shadow effect by the neighboring nanocolumns introduces the change of the In incorporation ratio into the InGaN QWs, and the mechanism is discussed. LED nanocolumn arrays, which consisted of n-type GaN nanocolumn, InGaN (1.5nm) / GaN (1.5nm) 25-pair superlattice, InGaN(3nm)/GaN(12 nm) 3 pair MQW, p-type 20nm-thick AlGaN electron blocking, and p-type 300nm-thick GaN layers, were fabricated. The green light emission was observed under the DC current injection at room temperature. Various GaN nanocolumn arrays of; triangular-lattice were prepared, at top regions of which 3-pair InGaN(3nm) /GaN(12nm) MQW were integrated. A strong two-dimensional light confinement is introduced at the Γ₁₁ photonic band edge wavelength, due to the periodic structure of nanocolumn arrays brings about . The laser action on 2D distributed feedback (DFB) scheme is expected, in which a lasing light emits vertically from the column top surface. Stimulated emission spectra were observed for the nanocolumn arrays under the 355 nm wavelength YAG laser light excitation. The emission peak wavelengths were changed from 520 to 566nm, depending on the shift of the band edge wavelength, which is caused by the lattice constant change from 240 to 270 nm as well as the nanocolumn diameter change from 200 to 240nm.