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A 100 nm thick InGaN/GaN multiple quantum-well column-crystallized thin film was deposited on Si(111) substrate, with InN as the interlayer, by molecular beam epitaxy. The diameter of the column crystal is about 40 nm. Transmission electron microscopy images showed clear five-period well layers. Photoluminescence measurements demonstrated a wide emission wavelength from about 500 to 800 nm with the full width at half maximum of 107 nm at room temperature. An unusual photoluminescence peak position shift was observed from the optical measurement. The selected area electron diffraction image demonstrated the hexagonal wurtzite structure of the column crystal. A self-supported GaN-based active subwavelength grating was proposed, and the active subwavelength grating structure was fabricated from the InGaN/GaN quantum-well thin film by a Si micromachining process.

GaN membrane structures are fabricated for micro-electro-mechanical systems (MEMS). The combination of GaN and Si semiconductors is promising for future MEMS. However, due to the different material properties, the fabrication of MEMS using GaN semiconductor is still limited. Here, a simple membrane of GaN semiconductor deposited on Si substrate was investigated. The GaN crystal was grown by molecular beam epitaxy and metal organic chemical vapor deposition. The basic properties of the fabricated GaN light emitting diode (LED) were investigated. Etching the Si substrate from the backside, a freestanding GaN LED membrane was fabricated which can be useful for micro total analysis system. From those experimental results, it was shown that the GaN LED membrane was feasible for MEMS applications.

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