Monolithically integrated III-Sb based laser diodes grown on miscut Si substrates

Abstract

We report the formation and growth characteristics of an interfacial misfit (IMF) array between AlSb and Si and their application to III-Sb based quantum well (QW) light-emitting devices including edge-emitting laser diodes and vertical-cavity surface emitting lasers (VCSELs) monolithically grown on a Si (001) substrate. A III-Sb epi-structure is grown monolithically on the Si substrate via a thin (=50 nm) AlSb nucleation layer. A 13% lattice mismatch between AlSb and Si is accommodated by using the IMF array. We demonstrate monolithic VCSELs grown on Si(001) substrates operating under room-temperature with optically-pumped conditions. A 3-mm pump spot size results in peak threshold excitation density of I th = 0.1 mJ/cm 2 and a multimode lasing spectrum peak at 1.62 μm. Moreover, broad-area edge-emitters consisting of GaSb/AlGaSb QWs are demonstrated under pulsed conditions at 77K with a threshold current density of ≅2 kA/cm 2 and a maximum peak output power of =20 mW for a 1 mm-long device. A use of 5° miscut Si substrates enables both IMF formation and suppression of an anti-phase domain, resulting in a drastic suppression of dislocation density over the III-Sb epi-layer and realization of electrically-injected laser diodes operating at 77 K. The current-voltage (I-V) characteristics indicate a diode turn-on of 0.7 V, which is consistent with a theoretical built-in potential of the laser diode. This device is characterized by a 9.1 Q forward resistance and a leakage current density of 0.7 A/cm 2 at -5 V and 46.9 A/cm 2 at -15 V. This IMF technique will enable the realization of III-Sb based electrically-injected VCSELs operating at the fiber-optic communication wavelength monolithically grown on a Si platform.