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We discuss physics, design, fabrication, performance, and selected applications of Deep Ultraviolet Light Emitting Diodes (DUV LEDs). Our analysis reveals the relative contributions of electrical injection, internal quantum efficiency, and light extraction efficiency to the overall DUV LED performance. Our calculations show that the reduction of the dislocation density at least below value of 2×108 1/cm3 is necessary for reaching high DUV LED efficiency. Better light extraction has been achieved using an innovative p-type transparent sub-contact layer and reflecting ohmic p-type contact resulting in nearly tripling DUV LED power. At high power dissipation, temperature rise might be significant, and we present data showing the power degradation with temperature increase and the results of the detailed 1D and 3D analysis of thermal impedance of DUV LEDs. As an example of DUV LED application, we report on microbial disinfection using 19 watt 275 nanometer DUV LED. [ABSTRACT FROM AUTHOR]

III-Nitride heterostructure field-effect transistors (HFETs) demonstrated a new paradigm in microwave switching and control applications due to unique combination of extremely low channel resistance (leading to low loss), very high RF power, low off-state capacitance, broad range of operating temperatures, chemical inertness and robustness. The paper reviews novel approaches and recent advances in III-Nitride technology for RF switching devices leading to higher operating frequencies and even lower insertion loss. [ABSTRACT FROM AUTHOR]

AlGaN epilayers with different aluminum content have been studied by photoluminescence (PL) and light-induced transient grating (LITG) techniques. The epilayers were grown by conventional metal organic chemical vapor deposition (MOCVD) and by migration enhanced MOCVD (MEMOCVDTM). The carrier lifetime and PL intensity in epilayers containing the same amount of aluminum are shown to be inversely proportional to the dislocation density. which was determined using etch pit technique. The carrier diffusion length is shown to be close to the average distance between two first-neighbor dislocations. Enhancement of the lifetime and PL intensity in epilayers grown on sapphire by MEMOCVDTM is demonstrated. [ABSTRACT FROM AUTHOR]

Unique materials properties of GaN-based semiconductors that make them promising for high-power high-temperature applications are high electron mobility and saturation velocity, high sheet carrier concentration at heterojunction interfaces, high breakdown field, and low thermal impedance (when grown over SiC or bulk AlN substrates). The chemical inertness of nitrides is another key property. An AlGaN/GaN Heterostructure Field Effect Transistor (HFET) has been a topic of intensive investigations since the first report in 1991 [1]. Several groups demonstrated high power operation of AlGaN/GaN HFETs at microwave frequencies [2,3,4], including a 100 W output power single chip amplifier developed by Cree, Inc. and devices with 100 GHz cut-off frequency reported in [5]. However, in spite of impressive achievements, the potential of nitride based HFETs has not been fully realized as yet. The RF powers expected from the fundamental properties of nitride based materials significantly exceed the experimental data. One of the key problems limiting the HFETs RF characteristics is high gate leakage currents causing DC and RF parameter degradation. When the gate voltage goes positive the forward leakage current shunts the gate-channel capacitance and thus limits the maximum device current. When the gate voltage is negative, high voltage drop between the gate and the drain causes premature breakdown and thus limits maximum applied drain voltage. In addition, gate leakage currents increase the device sub-threshold currents, which decrease the achievable amplitude of the RF output. These limitations become even more severe at high ambient temperatures. The characteristics of III-N HFETs can be considerably improved by implementing a new approach, which results from the demonstration of good quality of SiO2/AlGaN and Si3N4/AlGaN interfaces. This approach opens up a way to fabricate insulated gate heterostructure field-effect transistors (IGHFETs), which have the gate leakage currents several orders of magnitude below those of regular HFETs, and exhibit better linearity and higher channel saturation currents. In this chapter, we describe design, characterization and applications of these novel devices. [ABSTRACT FROM AUTHOR]

Our new Strain and Energy Band Engineering approach allows us to control, modulate or eliminate the strain thereby significantly enhancing the performance of electronic and optoelectronic devices on SiC and sapphire substrates using a new-pulsed atomic layer epitaxy procedure. New types of high power high temperature transistors with improved performance were fabricated. XRD, PL and AFM spectra are used to establish a high structural and optical quality of the quaternary multiple quantum wells. We have also demonstrated the use of PALE deposited quaternary AllnGaN multiple quantum wells in the active region ofa UV LED with emission ranging from 305 nm to 304 nm. [ABSTRACT FROM AUTHOR]

Presents a study that examined the low-frequency noise in aluminum-gallium-nitride thin films. Methodology; Comparison of the low-frequency noise in aluminum-gallium-nitride thin films and aluminum-gallium-nitride/gallium nitride heterostructure field effect transistors; Analysis of the temperature dependence of the low frequency noise.

Presents a study that investigated the low-frequency noise in a heterostructure field effect transistor and a metal oxide semiconductor heterostructure field effect transistor. Methodology; Comparison of the low-frequency noise in the two transistors; Analysis of the dependence of the low-frequency noise on the two-dimensional electron concentration.