Room-Temperature Operation of In_0.5Ga_0.5 As Quantum Dot Lasers Grown on Misoriented GaAs Substrates by Molecular Beam Epitaxy

We have investigated the characteristics of self-assembled In_0.5Ga_0.5As quantum dot lasers grown on three types of (100) GaAs substrates, i.e. 0°, 4° and 15°-tilted toward the (111)Ga plane. The lasing wavelength at room temperature is 1018 nm, 1015nm,and 1030 nm for the 0°, 4° and 15°-0ff samples, respectively. Due to the better quantum confinement and arrangement of the quantum dots, the 4o-off samples exhibit a lower threshold current of 47 mA at room temperature, compared to 73 and 65 mA for the 0° and 15°-off samples, respectively. For the same reason, the characteristic temperature obtained between 150 and 300 K is 117 K for the 4°-off samples, compared to 113 K and 100 K for the 0° and 15°-off samples, respectively.