Browsing by Author "Gu, GL"

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Novel approach to enhance the optical property in AlGaAs and InGaAlP by natural ordering during growth
(1996)
Chin, A
;
Lin, BC
;
Gu, GL
;
Hsieh, KY
;
Jou, MJ
Long range alloy ordering is observed by cross-sectional TEM in both (111)A and (111)B AlGaAs. We have measured a 31 meV photoluminescence (PL) peak energy red shift of (111)A and (111)B Al0.30Ga0.70As to that of (100), while the PL integrated intensity in (111)A and (111)B is near an order of magnitude larger than that of (100). The ordering effect is reduced at a high growth temperature of 700 degrees C and the best PL linewidth of 17 and 3 meV are obtained in (111)A Al0.40Ga0.60As and (111)B Al0.30Ga0.70As, respectively. In the In0.6Ga0.4P/InGaAlP MQW, similar ordering related PL peak energy red shift of 37 meV and similar to 2 times enhanced PL integrated intensity are observed for 0 degrees sample to that of 15 degrees.
Optical and structural properties of spontaneously formed long-range compositional modulation in (111)A and (111)B AlGaAs
(1996-06-01)
Chin, A
;
Lin, BC
;
Gu, GL
;
Hsieh, KY
;
電子工程學系及電子研究所
We have studied the spontaneously formed long-range Al-rich and Ga-rich AlxGa1-xAs/AlyGa1-yAs superlattices in both (111)A and (111)B AlGaAs during epitaxial growth. The spontaneously formed compositional modulation has been investigated by cross-sectional transmission electron microscopy in AlxGa1-xAs (x=0.3-0.4) grown on (111)A and (111)B GaAs substrates at 600-700 degrees C. In contrast, similar superstructures are not observed in layers simultaneously grown on (100) substrates. The observed structural compositional modulation is closely related to the large peak energy redshift and peak intensity enhancement in 15 K photoluminescence (PL) of samples grown on both (111)A and (111)B orientations to those on (100). The respective redshifts of PL peak energy for (111)A and (111)B Al0.27Ga0.73As to that of (100) are 137 and 45 meV, while the PL integrated intensity enhancement to (100) amounts to 200 and 2000 times, respectively. The effect of compositional modulation is reduced with the increasing growth temperatures as shown in the considerably less compositionally modulated (111)A and (111)B Al0.40Ga0.60As grown at 700 degrees C. (C) 1996 American Institute of Physics.