Paper TF-ThM3
Optical Radiation Selective Devices Based on III Nitrides

Thursday, October 18, 2007, 8:40 am, Room 613/614

Wide direct band gap of the III nitride materials allows for several advanced optoelectronic applications in a very wide spectral range from 200 nm to 1.77 µm. Both light emission sources and photodetectors with advanced properties can be achieved through tailoring layered III nitride structures with various layer order, chemical composition, conductivity and thickness. In addition, substrate selection plays an important role in the fabrication of these devices as well as in achieving desired device properties. Along with the efficiency of light emission or detection, in most cases it is important to provide selectivity of the optical radiation generated or sensed by the optical device. Such selectivity can be achieved by using spectral and polarization properties of optical radiation. In this paper we present results on the growth, processing, and modeling of multi-band photodiode structures, broad-spectrum avalanche LEDs, and polarization-sensitive photodetectors based on III nitrides grown by Radio Frequency Molecular beam epitaxy on silicon, sapphire, and lithium-aluminum oxide (LiAlO₂) substrates. Dual-band visible- and solar-blind UV/IR photodetectors as well as broad spectrum UV-enhanced avalanche LED structures have been demonstrated. The peak responsivities of the dual band photodetectors are 0.0038 and 0.055 A/W at the wavelengths of 349 nm and 1000 nm, respectively. The broad spectrum emission from the avalanche LEDs extended from 300 to 650 nm with a maximum at ~425 nm. Results on optimization of the dual-band photodiodes as well as on testing of polarization-sensitive GaN and InGaN photodetectors grown on non-polar LiAlO₂ substrates, which are currently in progress, will be presented in the final paper. Various advanced applications of the optical radiation sensitive devices based on III nitrides will be discussed.