We report gold-free growth of vertically aligned InAs/GaSb heterostructure nanowires (NWs) on Si(111) substrate by metal organic chemical vapor deposition technique. The effect of growth temperature on morphology and growth rate for InAs and InAs/GaSb heterostructure NWs were investigated. A combination of high material flow rates and optimum temperature (600 °C) has given better crystal quality of InAs nanowires. The morphology and shell thickness of NWs as observed by scanning electron microscope and transmission electron microscope (TEM) measurements can be tuned by the growth temperature. Electron microscopy also shows the formation of GaSb both in radial and axial directions outside the InAs NW core at certain growth temperatures. Crystal structure of InAs and InAs/GaSb heterostructure NWs was analyzed by high-resolution TEM and fast Fourier transform analysis. Using good crystalline InAs core grown at optimized growth temperature (600 °C), GaSb shell has been grown without any misfit dislocations at the core-shell interface. Basic electrical properties have been measured by forming ohmic contacts. I-V characteristics exhibit linear response indicating good ohmic behavior. These results show good control over InAs NWs growth, the GaSb shell thickness, and its crystal quality, which are essential for future nanoelectronic devices such as tunneling FET.
- Au-free nanowire growth
- InAs/GaSb hetero-structure
- metal organic chemical vapor deposition
- tunnelling field effect transistor