| The III-Nitride material system has already proven to be commercially viable for blue light emitting diodes (LEDs), blue laser diodes (LDs), and near UV photodetectors. Continued interest in this field has driven the desire for even lower emission and detection cut-off wavelengths into the solar-blind/deep UV portion of the spectrum. Military applications including chemical/biological agent detection and non-line-of-sight (NLOS) communications systems would both benefit from high-power, small size, low weight, robust deep UV emitters and detectors tuned to specific wavelengths. Commercial applications such as white LEDs for efficient, low cost lighting, high density optical data storage, higher resolution laser printing, air/water purification, food sterilization, in-situ activation of drugs, and activation of photochemically sensitive resins would benefit from the development of deep UV emitters. Nitride-based deep UV detectors may be used for UV exposure monitoring, power line fault monitoring, UV flame detection, combustion monitoring, early missile threat warning, aerial and terrestial UV countermeasures, and UV astronomy. Systems of UV emitters and detectors could be used for free-space UV communications and covert space communications. Most of these applications require lightweight, compact devices that can withstand harsh operating conditions. The III-nitride material system is uniquely suited to meet these needs due to its tunable, wide and direct band gap.;The III-nitride material system, however, faces significant device challenges including lack of a native substrate, difficulty in efficient doping of the material, current crowding effects, lack of appropriate metallic contacts, and etching difficulties. In order to achieve AlGaN-based deep UV emitters and detectors, it is necessary to achieve high aluminum compositions, which increases the band-gap of the material, exacerbating the above-mentioned difficulties.;This work primarily focuses on the device design, fabrication, and characterization of deep UV LEDs and UV APDs. However, the fabrication principles are also applied to deep UV detectors and focal plane arrays, and work towards achieving LDs and ZnO emitters is also presented. First, an introduction into UV emitters and detectors is presented including applications, alternative technologies, and the properties of the nitride material system. Next, some background information, including a brief survey of the key historical developments within the III-nitride material system, the basic theory of operation of LEDs, LDs, photodiodes, and APDs, and the challenges that face the development of UV optoelectronic devices, is discussed. Material growth, device measurement, device design, processing improvements, and device results are then presented for emitters in section four and detectors in section five. Section six concludes the paper while section seven discusses future work in this area. |
