Researchers from St Petersburg State University and partner institutions say they have shown for the first time that the orientation of gallium nitride nanowires on a silicon wafer can be controlled using a porous layer. The work was published in the journal Materials Science in Semiconductor Processing.
Left alone, these nanowires grow at an angle of about 55 degrees to the silicon surface, and the solutions used until now were complex, costly and multi-stage. The team used electrochemical etching to create a thin silicon layer with ordered nanopores, which act as templates and guide growth vertically, without the need for complex equipment.
The vertical nanowires showed photoluminescence more than three times as intense as that of tilted, disordered nanowires, as well as narrower emission lines, a sign of higher crystalline quality and fewer defects. According to the authors, the method could improve micro-LEDs, nanolasers and other light-emitting devices and, in the longer term, allow hybrid devices to be built directly on standard silicon wafers.
