M. Mehta

Epitaxial growth and formation of interfacial misfit array for tensile GaAs on GaSb

The authors report the formation of an interfacial misfit (IMF) array in the growth of relaxed GaAs bulk layers on a (001) GaSb surface. Under specific conditions, the high quality IMF array has a period of 5.6nm and can accommodate the 7.78% tensile GaAs∕GaSb lattice mismatch. The misfit site is identified as a 90° edge dislocation using Burger’s circuit theory and confirmed by high-resolution cross-section transmission electron microscopy (TEM) images. The resulting GaAs bulk material is both strain-free and highly crystalline. Plan-view TEM images show threading dislocation density of ∼3×106∕cm2. This material demonstration will enable novel device structures including an embedded GaSb active region in GaAs device matrix.

GaSb quantum-well-based “buffer-free” vertical light emitting diode monolithically embedded within a GaAs cavity incorporating interfacial misfit arrays

The authors demonstrate a monolithic, electrically injected, vertically emitting GaSb∕AlGaSb light emitting diode (LED) emitting at 1.6μm comprised of a hybrid GaAs∕GaSb-based structure. The LED is comprised of a GaSb∕AlGaSb quantum well/barrier active region embedded within high index contrast GaAs∕AlGaAs distributed Bragg reflectors (DBRs) using two interfacial misfit (IMF) arrays to relieve the strain induced from the high 8% lattice mismatch between the material systems. The first IMF is formed under compressive strain conditions to enable strain-free, defect-free deposition of GaSb active region directly on the lower GaAs∕AlAs DBRs without need for thick buffer. The second IMF is formed under tensile conditions to enable the upper GaAs∕AlAs DBRs on the GaSb active region. The device demonstrates a maximum output power of 3.5μW. Initial diode optical and electrical characteristics along with IMF band structure are discussed.

Room-Temperature Operation of Buffer-Free GaSb–AlGaSb Quantum-Well Diode Lasers Grown on a GaAs Platform Emitting at 1.65

Buffer-free growth of GaSb on GaAs using interfacial misfit (IMF) layers may significantly improve the performance of antimonide-based emitters operating between 1.6 and 3 mum by integrating III-As and III-Sb materials. Using the IMF, we are able to demonstrate a GaSb-AlGaSb quantum-well laser grown on a GaAs substrate and emitting at 1.65 mum, the longest known operating wavelength for this type of device. The device operates in the pulsed mode at room temperature and shows 15-mW peak power at -10degC and shows high characteristic temperature (To) for an Sb-based active region. Further improvements to IMF formation can lead to high-performance lasers operating up to 3 mum.

\mu

We report a GaSb/AlGaSb multi-quantum well diode laser emitting at 1550 nm at 77 K. The laser is grown directly on a GaAs substrate using interfacial misfit (IMF) arrays rather than thick metamorphic buffer layers.

m

We present a 1.65 μm GaSb/AlGaSb quantum-well (QW) laser operating at room temperature, grown buffer-free on a GaAs substrate. The enabling technology in this device is a layer of interfacial misfit dislocations (IMF) that completely relieve the strain between the GaAs substrate and the GaSb epi-layer without the use of thick metamorphic buffers. The IMF array is localized to the GaAs/GaSb interface, allowing current to pass through electrically pumped devices without the detrimental effects of threading dislocations that result in large voltage drops and non-radiative recombination. This growth technology provides an effective way of integrating III-Sb based devices such as IR-lasers, detectors and transistors with a higher quality and more scalable substrate such as GaAs.

1.55 μm GaSb/AlGaSb MQW diode lasers grown on GaAs substrates using interfacial misfit (IMF) arrays

We report on recent monolithically integrated III-V on Si device developments including a room-temperature, superluminescent light emitting diode. The integration scheme is enabled by spontaneously-formed, interfacial misfit arrays (IMF).

1.65 μm buffer-free GaSb/AlGaSb quantum-well diode lasers grown on a GaAs substrate operating at room temperature

We report the optical characteristics of type II GaSb quantum dot (QD) formation on GaAs by either Stranski-Krastanow (SK) or interfacial misfit (IMF) growth mode. The growth mode selection can be controlled by the gallium to antimony (III/V) ratio where a high III/V ratio produces IMF and a low III/V ratio establishes the SK growth mode. The IMF growth mode produces strain-free QDs emitting at 1.35 μm at room-temperature (RT), while the SK growth mode produces highly-strained QDs emitting at 1.18 μm at RT. We also demonstrate the fabrication of light-emitting diode (LED) structures containing five layers of GaSb/GaAs QDs using the IMF growth mode. Electroluminescence (EL) peak at 1.3 μm from the stacked QDs is observed at RT, which would be applicable to GaAs-based photonic devices for fiber-optic communication systems.