Browsing by Author "Hong, JMH"

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Growth and characterizations of GaN on SiC substrates with buffer layers
(1997-09-01)
Lin, CF
;
Cheng, HC
;
Chi, GC
;
Feng, MS
;
Guo, JD
High quality GaN epitaxial layers were grown on 6H-SiC substrates by using low-pressure metalorganic chemical vapor deposition method, Samples employing a three-period GaN/Al0.08Ga0.92N (100 Angstrom/100 Angstrom) as a buffer layer produce a good quality GaN epitaxial layer, with mobility and carrier concentration of 612 cm(2)/V.s and 1.3x10(17) cm(-3) (at 300 K), respectively, The enhanced electron mobility in the Al0.08Ga0.92N/GaN heterostructures is also observed, By using the van der Pauw method of Hall measurement, the sheet carrier density and mobility at 4.2 K for the Al0.08Ga0.92N/GaN heterostructure are 5.8x10(12) cm(-2) and 5300 cm(2)/V.s, respectively. Strong SdH (Shubnikov-de Haas) oscillations were observed to confirm the two-dimensional electron gas (2DEG) phenomenon at the AlGaN/GaN top heterointerface. In addition, an extra SdH oscillation also resulted from the high-duality 2DEG channel of the GaN/AlGaN bottom heterointerface. (C) 1997 American Institute of Physics.
Growth and characterizations of GaN on SiC substrates with buffer layers
(1997-09-01)
Lin, CF
;
Cheng, HC
;
Chi, GC
;
Feng, MS
;
Guo, JD
High quality GaN epitaxial layers were grown on 6H-SiC substrates by using low-pressure metalorganic chemical vapor deposition method, Samples employing a three-period GaN/Al0.08Ga0.92N (100 Angstrom/100 Angstrom) as a buffer layer produce a good quality GaN epitaxial layer, with mobility and carrier concentration of 612 cm(2)/V.s and 1.3x10(17) cm(-3) (at 300 K), respectively, The enhanced electron mobility in the Al0.08Ga0.92N/GaN heterostructures is also observed, By using the van der Pauw method of Hall measurement, the sheet carrier density and mobility at 4.2 K for the Al0.08Ga0.92N/GaN heterostructure are 5.8x10(12) cm(-2) and 5300 cm(2)/V.s, respectively. Strong SdH (Shubnikov-de Haas) oscillations were observed to confirm the two-dimensional electron gas (2DEG) phenomenon at the AlGaN/GaN top heterointerface. In addition, an extra SdH oscillation also resulted from the high-duality 2DEG channel of the GaN/AlGaN bottom heterointerface. (C) 1997 American Institute of Physics.
The dependence of the electrical characteristics of the GaN epitaxial layer on the thermal treatment of the GaN buffer layer
(1996-06-24)
Lin, CF
;
Chi, GC
;
Feng, MS
;
Guo, JD
;
Tsang, JS
The GaN buffer layer was grown on the sapphire substrate by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) at 525 degrees C. The following 1.3 mu m epitaxial GaN growth was carried out at 1025 degrees C. We varied the ramping rate from 12.5 to 100 degrees C/min to study the quality of the epitaxial GaN. It has been found that the x-ray peak width, photoluminescence (PL) linewidth, Hall mobilities, and carrier concentrations of GaN epitaxial layer strongly depend on the in situ thermal ramping rate. An optimum thermal ramping rate was found to be of 20 degrees C/min. The maximum mobility is 435 cm(2)/V s at carrier concentration of 1.7 x 10(17) cm(-3). The minimum full width at half maximum (FWHM) of x ray and PL were 5.5 min and 12 meV occur at a ramping rate of 20 degrees C/min. The decrease of the mobility at high and low ramping rate can be attributed to the thermal stress and the reevaporation of the GaN buffer layer. (C) 1996 American Institute of Physics.