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Title: Maskless regrowth of GaN for trenched devices by MOCVD

 [1];  [1];  [1];  [1];  [1]
  1. Electrical and Computer Engineering Department, University of California Santa Barbara, Santa Barbara, California 93106, USA
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 23; Related Information: CHORUS Timestamp: 2017-12-06 10:40:08; Journal ID: ISSN 0003-6951
American Institute of Physics
Country of Publication:
United States

Citation Formats

Agarwal, Anchal, Koksaldi, Onur, Gupta, Chirag, Keller, Stacia, and Mishra, Umesh K. Maskless regrowth of GaN for trenched devices by MOCVD. United States: N. p., 2017. Web. doi:10.1063/1.5003257.
Agarwal, Anchal, Koksaldi, Onur, Gupta, Chirag, Keller, Stacia, & Mishra, Umesh K. Maskless regrowth of GaN for trenched devices by MOCVD. United States. doi:10.1063/1.5003257.
Agarwal, Anchal, Koksaldi, Onur, Gupta, Chirag, Keller, Stacia, and Mishra, Umesh K. 2017. "Maskless regrowth of GaN for trenched devices by MOCVD". United States. doi:10.1063/1.5003257.
title = {Maskless regrowth of GaN for trenched devices by MOCVD},
author = {Agarwal, Anchal and Koksaldi, Onur and Gupta, Chirag and Keller, Stacia and Mishra, Umesh K.},
abstractNote = {},
doi = {10.1063/1.5003257},
journal = {Applied Physics Letters},
number = 23,
volume = 111,
place = {United States},
year = 2017,
month =

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 6, 2018
Publisher's Accepted Manuscript

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  • Characterized herein are quantum-well Hall devices in Si-delta-doped Al{sub 0.25}Ga{sub 0.75}As/GaAs and pseudomorphic Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs heterostructures, grown by low-pressure metal organic chemical vapor deposition method. The Si-delta-doping technique has been applied to quantum-well Hall devices for the first time. As a result high electron mobilities of 8,100 cm{sup 2}/V {center_dot} s with a sheet electron density of 1.5 {times} 10{sup 12} cm{sup {minus}2} in Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs structure and of 6,000 cm{sup 2}/V {center_dot} s with the sheet electron density of 1.2 {times} 10{sup 12} cm{sup {minus}2} in Al{sub 0.25}Ga{sub 0.75}As/GaAs structure have been achievedmore » at room temperature, respectively. From Hall devices in Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs structure, the product sensitivity of 420 V/AT with temperature coefficient of {minus}0.015%/K has been obtained. This temperature characteristics is one of the best results reported. Additionally, a high signal-to-noise ratio corresponding to the minimum detectable magnetic field of 45 nT at 1 kHz and 75 nT at 100 Hz has been attained. These resolutions are among the best reported results.« less
  • We have investigated the structural and electrical characteristics of (Ba{sub x}Sr{sub 1-x})Ti{sub 1+y}O{sub 3+z} (BST) thin films synthesized at 650{sup o}C on Pt/SiO{sub 2}/Si substrates using a large area, vertical metalorganic chemical vapor deposition (MOCVD) reactor equipped with a liquid delivery system. Films with a Ba/Sr ratio of 70/30 were studied, as determined using X-ray fluorescence spectroscopy (XRF) and Rutherford backscattering spectrometry (RBS). A substantial reduction of the dielectric loss was achieved when annealing the entire capacitor structure in air at 700{sup o}C. Dielectric tunability as high as 2.3:1 was measured for BST capacitors with the currently optimized processing conditions.
  • A ''post trenching'' aspect and soil conditions made it necessary for British Petroleum to plow-trench its 43.75-mile (70 km), concrete-coated 24-in. (610 mm) steel pipeline from the West Sole gas field offshore in the North Sea to the BP Easington Terminal. The capability to set a plow over an existing pipeline and to bury it in its prelaid location is an invaluable alternative to pretrenching techniques or to conventional jetting sleds. Design and modifications to equipment, instrumentation, control systems, and support vessels had to be performed in a 6-month period. Computer display CRT monitors onboard the barge helped insure thatmore » anchor movements and subsea activities remained a safe distance from another live gas pipeline along the route of the new line. Overall plowing rate average was 1.125 miles per day (1.8 km) or 1.25 m per minute (4.1 ft) on the offshore section.« less
  • Partitioning the soil surface CO{sub 2} flux (R{sub S}) flux is an important step in understanding ecosystem-level carbon cycling, given that R{sub S} is poorly constrained and its source components may have different responses to climate change. Trenched plots are a classic method of separating the R{sub S} source fluxes, but labor-intensive and may cause considerable disturbance to the soil environment. This study tested if various methods of plant suppression in trenched plots affected R{sub S} fluxes, quantified the R{sub S} response to soil temperature and moisture changes, and estimated the heterotrophic contribution to R{sub S}. It was performed inmore » a boreal black spruce (Picea mariana) plantation, using a complete randomized design, during the 2007 growing season (May-November). Trenched plots had significantly lower R{sub S} than control plots, with differences appearing {approx}100 days after trenching; spatial variability doubled after trenching but then declined throughout the experiment. Most trenching treatments had significantly lower (by {approx}0.5 {mu}mol m{sup -2} s{sup -1}) R{sub S} than the controls, and there was no significant difference in R{sub S} among the various trenching treatments. Soil temperature at 2 cm explained more R{sub S} variability than did 10-cm temperature or soil moisture. Temperature sensitivity (Q10) declined in the control plots from {approx}2.6 (at 5 C) to {approx}1.6 (at 15 C); trenched plots values were higher, from 3.1 at 5 C to 1.9 at 15 C. We estimated R{sub S} for the study period to be 241 {+-} 40 g C m{sup -2}, with roots contributing 64% of R{sub S} after accounting for fine root decay, and 293 g C m{sup -2} for the entire year. These findings suggest that laborious hand weeding of vegetation may be usefully replaced by other methods, easing future studies of this large and poorly-understood carbon flux.« less