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1.  Room temperature quantum cascade lasers with 27% wall plug efficiency
Y. Bai, N. Bandyopadhyay, S. Tsao, S. Slivken and M. Razeghi
Applied Physics Letters, Vol. 98, No. 18, p. 181102-1-- May 3, 2011 ...[Visit Journal]
Using the recently proposed shallow-well design, we demonstrate InP based quantum cascade lasers (QCLs) emitting around 4.9 μm with 27% and 21% wall plug efficiencies in room temperature (298 K) pulsed and continuous wave (CW) operations, respectively. The laser core consists of 40 QCL-stages. The highest cw efficiency is obtained from a buried-ridge device with a ridge width of 8 μm and a cavity length of 5 mm. The front and back facets are antireflection and high-reflection coated, respectively. The maximum single facet cw power at room temperature amounts to 5.1 W. [reprint (PDF)]
 
1.  Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs1−xSbx type-II superlattices
A. Haddadi, R. Chevallier, G. Chen, A. M. Hoang, and M. Razeghi
Applied Physics Letters 106 , 011104-- January 8, 2015 ...[Visit Journal]
A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm² under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm·Hz½·W-1 at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm² under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm·Hz½·W-1. [reprint (PDF)]
 
1.  High-quality MOCVD-grown heteroepitaxial gallium oxide growth on III-nitrides enabled by AlOx interlayer
Junhee Lee, Lakshay Gautam, and Manijeh Razeghi
Junhee Lee, Manijeh RazeghiAppl. Phys. Lett. 123, 151902 (2023) https://doi.org/10.1063/5.0170383 ...[Visit Journal]
We report high-quality Ga2O3 grown on an AlGaN/AlN/Sapphire in a single growth run in the same Metal Organic Chemical Vapor Deposition reactor with an AlOx interlayer at the Ga2O3/AlGaN interface. AlOx interlayer was found to enable the growth of single crystalline Ga2O3 on AlGaN in spite of the high lattice mismatch between the two material systems. The resulting nitride/oxide heterogenous heterostructures showed superior material qualities, which were characterized by structural, electrical, and optical characterization techniques. In particular, a significant enhancement of the electron mobility of the nitride/oxide heterogenous heterostructure is reported when compared to the individual electron mobilities of the Ga2O3 epilayer on the sapphire substrate and the AlGaN/AlN heterostructure on the sapphire substrate. This enhanced mobility marks a significant step in realizing the next generation of power electronic devices and transistors. [reprint (PDF)]
 
1.  Watt level performance of quantum cascade lasers in room temperature continuous wave operation at λ ∼ 3.76 μm
N. Bandyopadhyay, Y. Bai, B. Gokden, A. Myzaferi, S. Tsao, S. Slivken and M. Razeghi
Applied Physics Letters, Vol. 97, No. 13-- September 27, 2010 ...[Visit Journal]
An InP-based quantum cascade laser heterostructure emitting at 3.76 μm is grown with gas-source molecular beam epitaxy. The laser core is composed of strain balanced In0.76Ga0.24As/In0.26Al0.74As. Pulsed testing at room temperature exhibits a low threshold current density (1.5 kA/cm²) and high wall plug efficiency (10%). Room temperature continuous wave operation gives 6% wall plug efficiency with a maximum output power of 1.1 W. Continuous wave operation persists up to 95 °C. [reprint (PDF)]
 

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