Unipolar-light emitting diode like structures were grown by NH3 molecular beam epitaxy on c plane (0001) GaN on sapphire templates. Studies were performed to experimentally examine the effect of random alloy fluctuations on electron transport through quantum well active regions. These unipolar structures served as a test vehicle to test our 2D model of the effect of compositional fluctuations on polarization-induced barriers. Variables that were systematically studied included varying quantum well number from 0 to 5, well thickness of 1.5 nm, 3 nm, and 4.5 nm, and well compositions of In0.14Ga0.86N and In0.19Ga0.81N. Diode-like current voltage behavior was clearly observed due to the polarization-induced conduction band barrier in the quantum well region. Increasing quantum well width and number were shown to have a significant impact on increasing the turn-on voltage of each device. Temperature dependent IV measurements clearly revealed the dominant effect of thermionic behavior for temperatures from room temperature and above. Atom probe tomography was used to directly analyze parameters of the alloy fluctuations in the quantum wells including amplitude and length scale of compositional variation. A drift diffusion Schrödinger Poisson method accounting for two dimensional indium fluctuations (both in the growth direction and within the wells) was used to correctly model the turn-on voltages of the devices as compared to traditional 1D simulation models.
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14 May 2015
Research Article|
May 08 2015
Electron transport in unipolar InGaN/GaN multiple quantum well structures grown by NH3 molecular beam epitaxy
David A. Browne;
David A. Browne
1Materials Department,
University of California
, Santa Barbara, California 93106, USA
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Baishakhi Mazumder;
Baishakhi Mazumder
1Materials Department,
University of California
, Santa Barbara, California 93106, USA
2
Center for Nanophase and Materials Sciences
, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Yuh-Renn Wu;
Yuh-Renn Wu
3Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering,
National Taiwan University
, Taipei, Taiwan
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James S. Speck
James S. Speck
1Materials Department,
University of California
, Santa Barbara, California 93106, USA
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J. Appl. Phys. 117, 185703 (2015)
Article history
Received:
December 04 2014
Accepted:
April 23 2015
Citation
David A. Browne, Baishakhi Mazumder, Yuh-Renn Wu, James S. Speck; Electron transport in unipolar InGaN/GaN multiple quantum well structures grown by NH3 molecular beam epitaxy. J. Appl. Phys. 14 May 2015; 117 (18): 185703. https://doi.org/10.1063/1.4919750
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