Efficient free exciton emission at room temperature in Zn0.5Cd0.5Se/MgxZnyCd1−x−ySe quantum wells

We use temperature and power-dependent photoluminescence spectroscopy to demonstrate efficient free exciton emission at room temperature in high quality, strongly confining Zn0.5Cd0.5Se/MgxZnyCd1−x−ySe quantum wells. Our measurements indicate that at low temperatures (T<50 K), the luminescence is dominated by bound exciton emission. However, free exciton emission becomes dominant at high temperatures (T>100 K) and persists up to room temperature with an intensity that is ∼40% that at cryogenic temperatures. We attribute these observations to the deep confinement potential that stabilizes excitons and prevents their thermal escape.