MBE growth conditions for 1.3 μm light emission from InAs quantum dots

InAs/GaAs quantum dots grown by molecular beam epitaxy (MBE) at extremely low growth rates of only 0.01 monolayers per second and a growth temperature of 500°C result in low density and large free standing islands. We show that shape and photoluminescence (PL) spectra change drastically if the capping temperature is reduced from 500°C to 400°C. At high capping temperatures flat 3 nm high lens shaped islands are identified in transmission electron microscopy (TEM) whereas at lower capping temperatures islands stay 6 nm in height and the emission wavelength shifts from 1113 nm to 1200 nm. The later corresponds to 1.294 μm at room temperature. Based on our investigation an Al-free light emitting diode (LED) is fabricated