Study of Optical Properties of Disk Geometry Microresonators with Active Region Based on InGaN/GaN Quantum Wells

The aim of this work is to study the optical properties of III-N semiconductor heterostructures on Al2O3 and Si substrates and disk microresonators (MD) with InGaN/GaN quantum wells developed from heterostructure on Al2O3 substrate. Optical properties were studied by means of photoluminescence (PL) spectroscopy. Diameters of MDs were varied from 1 μm to 12 μm. PL spectra of the MDs and III-N semiconductor heterostructures on Al2O3 and Si substrates were studied at room temperature using a confocal optical system Confotec NR500. For each III-N semiconductor heterostructure and MD diameter PL spectra were obtained in a wide range of optical excitation densities. It is shown that III-N semiconductor heterostructures on Al2O3 and Si substrates have high optical quality. MDs support the propagation of high-Q whispering gallery modes. Transition to the stimulated emission is demonstrated for III-N heterostructure on a Si substrate at wavelength ~420 nm under optical pumping through cylindrical lens in pulse regime at room temperature. The results obtained confirm that the studied III-N semiconductor heterostructures on Al2O3 and Si substrates are promising for creation III-N semiconductor microlasers supporting whispering gallery modes with high stability of characteristics.