1.54 lm GaSb/AlGaSb multi-quantum-well monolithic laser at 77 K grown on miscut Si substrate using interfacial misfit arrays

Growth and fabrication: In this Letter, we present a GaSb quantumwell (QW) laser diode monolithically grown on a 5 miscut Si (100) substrate. The device operates at a wavelength of 1.54 m mu nder pulsed conditions at 77 K. The 13% lattice mismatch at AlSb=Si interface is spontaneously relieved by an interfacial misfit array (IMF), resulting in low-defect density, single-domain III-Sb bulk material, on which the laser is grown. The schematic of the device is shown in Fig. 1. The entire epi-structure is grown using molecular beam epitaxy (MBE) at 400C. The epitaxy is initiated with a 50 nm AlSb nucleation layer that is optimised for simultaneous IMF formation and APD suppression on Si. The AlSb layer is followed by a 2 mm n-GaSb contact layer, a 2.3 m mA l0.55Ga0.45Sb lower n-type clad, a 0.3 mm undoped Al0.3Ga0.7Sb waveguide layer surrounding the QW active region, a 1.5 m mA l0.55Ga0.45Sb upper p-type clad and a highly doped 50 nm GaSb p-type contact layer. The active region comprises six GaSb (10 nm) QWs separated by Al 0.3Ga0.7Sb (10 nm) barrier layers. The samples are processed such that they form gain-guided stripe lasers with widths ranging from 25 to 100 mm. The process involves an inductively coupled plasma reactive ion etch (ICP-RIE) into the n-GaSb contact layer using boron trichloride (BCl3 )c hemistry, Ti=Pt=Au metal evaporations to both the n-GaSb and p-GaSb contact layers. The Si substrate is thinned to 70 m ma nd cleaved to bar lengths of 1 mm. Poor facet quality along with the low gain of the