Center for Quantum Devices - Journal Articles and Conference Proceedings

Page 1 (3 Items)

1.	Al_xGa_1-xN-based back-illuminated solar-blind photodetectors with external quantum efficiency of 89% E. Cicek, R. McClintock, C. Y. Cho, B. Rahnema, and M. Razeghi Appl. Phys. Lett. 103, 191108 (2013)-- November 5, 2013 We report on high performance Al_xGa_1−xN-based solar-blind ultraviolet photodetector (PD) array grown on sapphire substrate. First, high quality, crack-free AlN template layer is grown via metalorganic chemical vapor deposition. Then, we systematically optimized the device design and material doping through the growth and processing of multiple devices. After optimization, uniform and solar-blind operation is observed throughout the array; at the peak detection wavelength of 275 nm, 729 μm² area PD showed unbiased peak external quantum efficiency and responsivity of ∼80% and ∼176 mA/W, respectively, increasing to 89% under 5 V of reverse bias. Taking the reflection loses into consideration, the internal quantum efficiency of these optimized PD can be estimated to be as high as ∼98%. The visible rejection ratio measured to be more than six orders of magnitude. Electrical measurements yielded a low-dark current density: <2 × 10⁻⁹ A/cm², at 10 V of reverse bias. reprint
2.	Al_xGa_1−xN-based solar-blind ultraviolet photodetector based on lateral epitaxial overgrowth of AlN on Si substrate E. Cicek, R. McClintock, C. Y. Cho, B. Rahnema, and M. Razeghi Appl. Phys. Lett. 103, 181113 (2013)-- October 30, 2013 We report on Al_xGa_1−xN-based solar-blind ultraviolet (UV) photodetector (PD) grown on Si(111) substrate. First, Si(111) substrate is patterned, and then metalorganic chemical vapor deposition is implemented for a fully-coalesced ∼8.5 μm AlN template layer via a pulsed atomic layer epitaxial growth technique. A back-illuminated p-i-n PD structure is subsequently grown on the high quality AlN template layer. After processing and implementation of Si(111) substrate removal, the optical and electrical characteristic of PDs are studied. Solar-blind operation is observed throughout the array; at the peak detection wavelength of 290 nm, 625 μm² area PD showed unbiased peak external quantum efficiency and responsivity of ∼7% and 18.3 mA/W, respectively, with a UV and visible rejection ratio of more than three orders of magnitude. Electrical measurements yielded a low-dark current density below 1.6 × 10⁻⁸ A/cm² at 10 V reverse bias. reprint
3.	Surface plasmon enhanced light emission from AlGaN-based ultraviolet light-emitting diodes grown on Si (111) Chu-Young Cho, Yinjun Zhang, Erdem Cicek, Benjamin Rahnema, Yanbo Bai, Ryan McClintock, and Manijeh Razeghi Appl. Phys. Lett. 102, 211110 (2013)-- May 31, 2013 We report on the development of surface plasmon (SP) enhanced AlGaN-based multiple quantum wells (MQWs) ultraviolet (UV) light-emitting diodes (LEDs) grown on silicon (111) substrates. In order to generate SP-coupling with the radiating dipoles in MQWs, an aluminum layer is selectively deposited in holes etched in the top p-AlGaN to p-GaN layers. After flip-chip bonding and substrate removal, an optical output power of ∼1.2 mW is achieved at an emission wavelength of 346 nm; the output power of these UV LEDs with Al layer is increased by 45% compared to that of conventional UV LEDs without Al layer. This enhancement can be attributed to an increase in the spontaneous emission rate and improved internal quantum efficiency via resonance coupling between excitons in MQWs and SPs in the aluminum layer. reprint

Page 1 (3 Items)