Paper MS-MoA10
Development of III-Nitrides for Energy Harvesting Applications

Monday, November 7, 2016, 4:40 pm, Room 103A

III-Nitride wide-bandgap semiconductors have recently enabled state-of-the-art technologies for energy harvesting applications, such as photovoltaics and thermoelectrics. III-Nitride materials and devices have provided tremendous advantages due to their distinguished features, including tunable bandgap, superior electrical properties, high-temperature stability, enhanced chemical stability, and mechanical strength. Furthermore, InGaN with indium compositions up to 30% (2.5 eV band gap) have been developed for photovoltaic applications by controlling defects and phase separation. Additionally, InGaN solar cell design consists of 2.9 eV InGaN p-n junction sandwiched between p- and n-GaN layers results in internal quantum efficiencies as high as 50%; while devices utilizing a novel n-GaN strained window-layer enhanced the open circuit voltage. These results establish the potential of III-Nitrides and related materials in ultra-high efficiency photovoltaics. Moreover, thermoelectrics, conversion of waste thermal energy into electrical energy, have seen pioneering developments over the past 20 years. A figure of merit ZT, used to measure the efficiency of the thermoelectric materials. Various approaches have been taken to increase the efficiency of thermoelectric materials, such as electron quantum confinement and phonon scattering to increase the power factor and decrease the lattice thermal conductivity, respectively. The objectives of this study are to highlight the use of III-Nitrides in high efficient photovoltaic and thermoelectric energy harvesting applications. Some recent measurements of the thermoelectric properties–the Seebeck coefficient, the electrical conductivity and the power factor–of GaN and InGaN thin films will also be reported.