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108 results on '"Osotchan, T."'

12. Transition in (001) AlGaAs/AlAs/GaAs double-barrier quantum structure for infrared photodetection

Author

Osotchan, T., Chin, V.W.L., and Tansley, T.L.

Subjects
Quantum wells -- Research, Quantum electronics -- Research, Superlattices as materials -- Research, Physics
Abstract

Optical transitions for the (001) Al0.3Ga0.7As/AlAs/GaAs double-barrier superlattices are examined by a semiempirical, tight-binding computation. The oscillator strength between the hole and electron states confined in either gamma- or X-like well are studied as a function of AlAs slab thickness. Intersub-band transition within the conduction band, including gamma- and X-like superlattice states, is examined for a quantum well infrared photodetector (QWIP). Results show that for a specific design structure, the dual wavelength QWIP can be attained with comparable oscillator strength for the 3-5 microns and 8-14 microns atmospheric windows.

Published
1996

13. Electron mobilities in gallium, indium, and aluminum nitrides

Author

Chin, V.W.L., Tansley, T.L., and Osotchan, T.

Subjects
Semiconductors -- Research, Nitrides -- Analysis, Electron mobility -- Analysis, Physics
Abstract

Electron mobility in GaN and InN, which was maximum when the temperature ranged between 100 and 200 Kelvin, was dependent on compensation ratio and electron density was highest at low temperatures. The variation principle was used to calculate electron mobility as a function of temperature at various carrier concentrations. These compounds, which exhibited wide direct band gaps, were used in several optoelectronic device applications.

Published
1994

22. Tailoring deep level surface defects in ZnO nanorods for high sensitivity ammonia gas sensing

Author

Anantachaisilp, S, Smith, SM, Ton-That, C, Osotchan, T, Moon, AR, Phillips, MR, Anantachaisilp, S, Smith, SM, Ton-That, C, Osotchan, T, Moon, AR, and Phillips, MR

Abstract

© 2014 American Chemical Society. The influence of deep level surface defects on electrical and gas sensing properties of ZnO nanorods NH3(g) sensors was studied. ZnO nanorods 50-60 nm in diameter were synthesized via low-temperature hydrothermal growth at 90°C on sapphire substrates. The as-grown nanorods exhibited a cathodoluminescence (CL) peak centered at 1.90 eV (YL), attributed to LiZn deep acceptors or O interstitials. Subsequent annealing in O2 at 1 atm and Zn vapor at 650°C produced broad CL peaks centered at 1.70 eV (RL) and 2.44 eV (GL), respectively. The RL and GL have been ascribed to acceptor-like VZn and donor-like VO related centers, respectively. Electrical and gas sensing measurements established that the NH3 gas response sensitivity was 22.6 for O2 anneal (RL), 1.4 for Zn vapor anneal (GL), and 4.1 for the as-grown (YL) samples. Additionally, treatment in H-plasma quenched the RL and inverted the NH3 electrical response due to the incorporation of H donors. Changes in the gas sensing response are explained by a shift in the position of the ZnO Fermi level relative to the chemical potential of NH3 gas due to the creation of near surface donor or acceptors. These data confirm that ZnO nanorods arrays can be tailored to detect specific gas species. (Chemical Equation Presented).

Published
2014

44. ScienceAsia

Author

LEELAPRUTE, S., primary, TANC, LM., additional, and OSOTCHAN, T., additional

Published
1997
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