Alternating molecular beam epitaxy and characterization of InGaAs quantum dots and quantum dot lasers

Alternating molecular beam epitaxy is used to grow quantum dots of InGaAs on GaAs via the Stranski-Krastanow growth transition. These quantum dots can emit light at wavelengths as long as 1320 nm at room temperature. Quantum dot lasers have been grown and fabricated using methods that are practically identical to those used to form quantum well lasers. The quantum dot lasers exhibit very strong state-filling. At room temperature, state-filling leads to lasers whose lasing wavelength depends strongly on the threshold current densities and thus have more state-filling and a correspondingly longer wavelength emission than longer lasers. These state-filling effects are less pronounced as the laser is cooled and the threshold current density decreased. This leads to a compensation of the bandgap increase with decreasing temperature, yielding lasers that have a very stable lasing wavelength over the temperature range of 80-300 K.