Browsing by Author "HSIEH, KY"

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SPONTANEOUS FORMATION OF AL RICH AND GA RICH ALXGA1-XAS/ALYGA1-YAS SUPERLATTICE AND STRONG ENHANCEMENT OF OPTICAL-PROPERTIES
(1994-10-10)
CHIN, A
;
HSIEH, KY
;
LIN, HY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Long range composition ordering and spontaneous formation of Al rich and Ga rich AlxGa1-xAs/AlyGa1-yAs superlattice were demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in a 280 angstrom Al0.4GaAs quantum well laser diode heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates. On the contrary, none of above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. More evidence is shown in the (111)B Al0.7GaAs barriers which were disordered due to a high growth temperature and did not show any superstructure. 10 K photoluminescence was shown with 32 meV redshift and a 12-times peak intensity enhancement in (111)B orientation. (C) 1994 American Institute of Physics.
SPONTANEOUSLY FORMED LONG-RANGE AL-RICH AND GA-RICH ALXGA1-XAS/ALYGA1-YAS SUPERLATTICE AND OPTICAL-PROPERTIES ENHANCEMENT IN (111)A ALGAAS
(1995-12-11)
CHIN, A
;
LIN, BC
;
GU, GL
;
HSIEH, KY
;
電子工程學系及電子研究所
Spontaneously formed long-range Al-rich and Ga-rich AlxGa1-xAs/AlyGa1-yAs superlattice in(111)A was demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in 0.75 mu m Al0.30Ga0.70As grown on (111)A GaAs substrates at 640 degrees C. In contrast, none of the above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. 15 K photoluminescence (PL) showed a 31 meV redshift and six times peak intensity enhancement in layers grown on (111)A substrates to that on (100). A reduced long-range compositional modulation can be achieved by growth at higher temperatures and is shown in the finer and moderately modulating (111)A Al0.40Ga0.60As grown at 700 degrees C. A 15 K PL linewidth of 17 meV was achieved in 700 degrees C grown (111)A A(0.40)Ga(0.60)As that is the narrowest reported linewidth for (111)A AlGaAs. (C) 1995 American Institute of Physics.
STRONG ACCUMULATION OF AS PRECIPITATES IN LOW-TEMPERATURE INGAAS QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY
(1994-03-21)
CHENG, TM
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CHIN, A
;
CHANG, CY
;
HUANG, MF
;
HSIEH, KY
Low temperature InGaAs strained quantum wells have been grown by molecular beam epitaxy and annealed at 600-900-degrees-C for 10 min. For an optimized annealing condition, arsenic precipitates can be successfully confined in the InGaAs wells and completely depleted in the GaAs barriers. The strong accumulation of As precipitates shows that the phenomena are not due to the strain effect but may be explained by the difference of interfacial energy between precipitate and matrix. The ability to control the As precipitates into two-dimensional quantum wells in LT materials has unique applications in a wide variety of devices.
STRONG ENHANCEMENT OF THE OPTICAL AND ELECTRICAL-PROPERTIES, AND SPONTANEOUS FORMATION OF AN ORDERED SUPERLATTICE IN (111)B ALGAAS
(1995-05-01)
CHIN, A
;
LIN, HY
;
HSIEH, KY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Strong enhancement in the luminescence intensity is observed in Al0.22Ga0.78As epitaxial layers grown on misoriented (111)B GaAs as compared to those simultaneously grown on (100) GaAs. For a 1 degrees misorientation the luminescence intensity is almost 10 to 1000 times that of the (100) layers, depending on the growth temperature. Room temperature electron mobility for 3 degrees misoriented (111)B Al0.18Ga0.82As is 19% higher than that for side-by-side grown (100). The strong luminescence associated with a large red shift of 90 meV and the 19% mobility enhancement are related to the long range composition ordering in (111)B AlGaAs, which is observed by cross-sectional transmission electron microscopy in a 280 Angstrom Al0.4GaAs quantum well heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates.