Browsing by Author "Chen, W. R."

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GaN p-i-n photodetectors with an LT-GaN interlayer
(2008-04-01)
Lin, J. C.
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Su, Y. K.
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Chang, S. J.
;
Lan, W. H.
;
Huang, K. C.
Nitride-based p-i-n ultraviolet (UV) photodetectors with a low-temperature (LT) GaN interlayer were proposed and fabricated. Compared with a conventional GaN p-i-n photodetector, it was found that both the dark current and ideality factor of the p-i-n photodetector with an LT-GaN interlayer became larger whereas the UV-to-visible rejection ratio became smaller because of the poor crystal quality of the LT-GaN interlayer. However, the responsivity of the GaN p-i-n photocletector with an LT-GaN interlayer was larger than that of the conventional GaN p-i-n photocletector under a high reverse bias because of the carrier multiplication effect and/or internal gain that originated from the defect levels.
GaN-based light-emitting diodes prepared on vicinal sapphire substrates
(2007-02-01)
Lin, J. C.
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Su, Y. K.
;
Chang, S. J.
;
Lan, W. H.
;
Huang, K. C.
Thin InGaN epitaxial layers and GaN-based light-emitting diodes (LEDs) on conventional and vicinal cut sapphire substrates are prepared. It is found that indium atoms are distributed much more uniformly in the samples prepared on vicinal cut sapphire substrates. It is also found that stronger electroluminescence intensity can be achieved without the band-filling effect of localised states from the LEDs with vicinal cut sapphire substrate. With 20 mA current injection, it is found that 44% electroluminescence intensity enhancement can be achieved by using the 1 degrees tilted sapphire substrate.
High responsivity of GaN p-i-n photodiode by using low-temperature interlayer
(2007-10-22)
Lin, J. C.
;
Su, Y. K.
;
Chang, S. J.
;
Lan, W. H.
;
Huang, K. C.
Gallium nitride p-i-n ultraviolet photodiodes with low- temperature (LT)- GaN interlayer have been fabricated. It was found that the dark current of photodiode with LT- GaN interlayer is as small as 143 pA at 5 V reverse bias. It was also found that the responsivity of the photodiode with LT- GaN interlayer can be enhanced at a small electric field (similar to 0.4 MV/cm) due to the carrier multiplication effect. The UV photocurrent gain of 13 and large ionization coefficient (alpha = 3.1 X 10(5) cm(-1)) were also observed in the detector with LT- GaN interlayer. Furthermore, we can achieve a large peak responsivity of 2.27 A/W from the photodiode with LT- GaN interlayer. (C) 2007 American Institute of Physics.
Low dark current GaN p-i-n photodetectors with a low-temperature AIN interlayer
(2008-07-01)
Lin, J. C.
;
Su, Y. K.
;
Chang, S. J.
;
Lan, W. H.
;
Chen, W. R.
GaN p-i-n ultraviolet (UV) photodetectors (PDs) with a low-temperature (LT)-AIN interlayer were proposed and fabricated. It was found that the dark current of such detectors is as small as 28pA even at a high reverse bias of 40 V. Although the high potential barrier at the AIN-GaN interface would slightly reduce the responsivity of PD under low reverse biases, the high UV-to-visible rejection ratio of the PD with an LT-AIN interlayer could be achieved under high reverse biases due to its very low dark current. The rejection ratio of the PD with the LT-AIN interlayer is as large as 735 at the reverse bias of 40 V.