Browsing by Author "Ou-Yang, MC"

Now showing 1 - 4 of 4

Characterization of InGaN/GaN multiple quantum well nanorods fabricated by plasma etching with self-assembled nickel metal nanomasks
(2005-04-01)
Hsueh, TH
;
Huang, HW
;
Kao, CC
;
Chang, YH
;
Ou-Yang, MC
High-density (3.0 x 1010 cm (-2)) InGaN/GaN Multiple quantum well (MQW) nanorods were fabricated from an as-grown bulk light-emitting diode structure by inductively coupled plasma dry etching with self-assembled nickel metal nanomasks. The self-assembled nickel metal nanomasks were formed by rapid thermal annealing of a nickel metal film at 850 degrees C for 1 min. The influence of the thicknesses of the Ni metal film on the dimensions and density of the nanorods was also investigated. The structural and optical properties of the InGaN/GaN MQW nanorods were established using field emission scanning electron microscopy, transmission electron microscopy and photoluminescence measurements. The diameters and heights of nanorods were estimated to be 60 to 100nm and more than 0.28 mu m, respectively. The peak emission wavelength of the nanorods showed a blue shift of 5.1 nm from that of the as-grown bulk. An enhancement by a factor of 5 in photoluminescence intensity of the nanorods compared with that of the as-grown bulk was observed. The blue shift is attributed to strain relaxation in the wells after dry etching, the quantum confinement effect, or a combination of the two, which results in the enhancement of emission intensity.
Fabrication and characterization of In(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl(2)/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Fabrication and characterization of In0.25Ga0.75N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl-2/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Pumping intensity dependent surface charge accumulation and redshifted microphotoluminescence of silicon-implanted quartz
(2004-08-09)
Lin, GR
;
Yu, KC
;
Lin, CJ
;
Kuo, HC
;
Ou-Yang, MC
The pumping-intensity dependency of nanocrystallite silicon (nc-Si) related microphotoluminescence (mu-PL) from multirecipe Si-implanted quartz is characterized. After annealing at 1100degreesC for 3 h, themu-PL at 724 nm contributed by nc-Si with a diameter of about 4 nm is maximized. By increasing the pumping intensity from 10 kW/cm(2) to 300 kW/cm(2), the mu-PLs of 1 and 3-h-annealed Si-implanted quartz samples are redshifted by <1.2 and 11 nm, respectively. The mu-PL of 3-h-annealed sample further redshifts by 2.5 nm after pumping at 300 kW/cm(2) for h. Such a redshift in PL is attributed to the anomalous quantum Stark effect under strong illumination, which photoionizes the buried nc-Si and initiates an electric field beneath the surface of Si-implanted quartz. The measurement of accumulating charges and voltage drop during illumination primarily elucidate the correlation between redshift in PL and the photoionized nc-Si induced surface electric field. (C) 2004 American Institute of Physics.