Investigation of High Composition InGaN Siddharth Rajan, Ohio State University, DMR 1106177

1. Investigation of High Composition InGaNSiddharth Rajan, Ohio State University, DMR 1106177 • III-Nitride emitters are technologically important for various applications such as solid state lighting and diode lasers. In this work, we have made new discoveries relating to • Synthesis of high composition InGaN in a new N-rich growth regime • Carrier transport in GaN/InGaN/GaN heterostructures along the N-polar orientation • Optical characteristics of GaN/InGaN/GaN heterostructures • Using the high-composition InGaN heterostructures developed under this project, we demonstrated mitigation of carrier overshoot and efficiency droop by using the N-polar or inverted LED orientation. This is the first demonstration of a N-polar green LED, and helps to understand the electronic and optical properties of III-Nitride emitters. Figure1: N-polar green Light Emitting Diode with reduced efficiency droop F. Akyol, D N Nath, S Krishnamoorthy,P S Park, and S. Rajan, "Suppression of Electron Overflow and Efficiency Droop in N polar GaN Green LEDs", Applied Physics Letters, 100, 111118 (2012).

2. Investigation of High Composition InGaNSiddharth Rajan, Ohio State University, DMR 1106177 Technological Impact Efficiency droop is one of the most important issues facing the LED industry today. Our experimental and simulation results demonstrate that using inverted polarity structures could help to mitigate this issue. This work could have important impact on the solid state lighting industry and the laser industry. Graduate education One graduate student and one visiting scholar are supported by this grant. Figure 2: Energy diagram of a N-polar LED under bias. Device simulations show that inverted polarity LEDs could have lower turn-on voltage, leading to higher efficiency lighting.