Browsing by Author "CHENG, TM"

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2-DIMENSIONAL ARSENIC PRECIPITATION BY IN DELTA-DOPING DURING LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY GROWTH OF GAAS OR ALGAAS
(1994-05-09)
CHENG, TM
;
CHANG, CY
;
CHIN, A
;
HUANG, MF
;
HUANG, JH
Low temperature (LT) GaAs delta doped with In and Al have been grown by molecular beam epitaxy and annealed at 600-900-degrees-C for 10 min. As precipitates have been observed to form preferentially on In doping planes while depleting on the Al planes. Similar As precipitates in In-doped LT-Al0.25Ga0.75As are 50% more efficient than that of GaAs. The accumulation or depletion of As precipitates in two-dimensional planes in LT materials using isoelectronic impurities show that the phenomena is not directly related to the electronic properties of dopant impurities and therefore has many device applications.
AS PRECIPITATE REDISTRIBUTION IN SI DELTA-DOPED LOW-TEMPERATURE GAAS
(1994-11-15)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
CONTROL OF AS PRECIPITATION IN LOW-TEMPERATURE GAAS BY ELECTRONIC AND ISOELECTRONIC DELTA-DOPING
(1995-02-01)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A systematic study of electronic (Si and Be) and isoelectronic (In and Al) delta-doping effects on the formation of arsenic precipitates in GaAs grown by molecular beam epitaxy (MBE) at low substrate temperature is presented. Both electronic dopant Si and isoelectronic dopant In are found to accumulate As precipitates in postgrowth-annealed samples, while the precipitate accumulation effect is more prominent for Si than In. As precipitate is depleted from regions doped with Be or Al. The results suggest that the electronic property of impurity does not have a direct correlation with the As precipitation process. The effects of doping concentration and postgrowth annealing temperatures are also reported. The ability to control the As precipitates in low-temperature materials should lead to a wide variety of device applications.
FORMATION AND CHARACTERIZATION OF GAAS/AS SUPERLATTICE GROWN BY MOLECULAR-BEAM EPITAXY AT LOW SUBSTRATE-TEMPERATURE
(1995-05-01)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
High-resolution X-ray diffractometer and transmission electron microscope (TEM) are used to characterize the redistribution of As precipitates in Si delta-doped GaAs grown by molecular beam epitaxy at low substrate temperature (230 degrees C). The superlattice satellite peaks are observed for samples annealed at 700-800 degrees C for 10 min, which is attributed to the formation of a GaAs/As superlattice during the annealing period. The degree of As precipitates confined on the delta-doped planes is revealed on the intensity of satellite peaks in the X-ray rocking curves, as confirmed by the TEM observations. The lattice expansion and contraction of the annealed low-temperature epitaxial layers can be easily observed from the asymmetry of the satellite peaks.
HIGH-RESOLUTION X-RAY CHARACTERIZATION OF LOW-TEMPERATURE GAAS/AS SUPERLATTICE GROWN BY MOLECULAR-BEAM EPITAXY
(1994-06-27)
CHENG, TM
;
CHANG, CY
;
CHANG, TC
;
HUANG, JH
;
HUANG, MF
High-resolution x-ray analysis of Si delta-doped GaAs grown by molecular-beam epitaxy at a low substrate temperature (230-degrees-C) is presented. Superlattice satellite peaks in the rocking curve are observed for the sample annealed at 700-degrees-C for 10 min. The peak intensity increases with increasing postgrowth annealing temperature and reaches the maximum value for the 900-degrees-C annealed sample. The evolution of the x-ray rocking curves can be explained consistently by the formation of a GaAs/As superlattice during the annealing period based on the transmission electron microscope observations.
LUMINESCENCE OF LOW-TEMPERATURE GAAS IN A GAAS/IN0.2GA0.8AS MULTIPLE-QUANTUM-WELL STRUCTURE
(1995-04-17)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
STRONG ACCUMULATION OF AS PRECIPITATES IN LOW-TEMPERATURE INGAAS QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY
(1994-03-21)
CHENG, TM
;
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 LUMINESCENCE INTENSITIES IN AL0.22GA0.78AS GROWN ON MISORIENTED (111)B GAAS
(1993-10-25)
CHIN, A
;
CHENG, TM
;
PENG, SP
;
OSMAN, Z
;
DAS, U
Strong enhancement in the luminescence intensity is observed in Al0.22Ga0.78As epitaxial layers grown on misoriented (111)B GaAs at 636-degrees-C. For 3-degrees misorientation, the luminescence intensity is almost 10 times that of (100) layers and the luminescence efficiency is an order of magnitude stronger than that of (100). (100) Al0.4Ga0.6As/GaAs quantum well laser diode structures grown under identical conditions with a low threshold current density of 150 A/cm2 are indications of excellent AlGaAs material quality. Electron mobility for 3-degrees misoriented (111) Al0.25Ga0.75As is about 10% higher than that for side-by-side grown (100). The strong luminescence associated with a large red shift of 90 meV, the 10% mobility enhancement, and wirelike structure shown in transmission electron microscopy are indicative of the natural formation of quantized structures.
SUBSTRATE ORIENTATION DEPENDENCE OF LOW-TEMPERATURE GAAS GROWN BY MOLECULAR-BEAM EPITAXY
(1995-01-02)
CHENG, TM
;
CHANG, CY
;
HUANG, JH
;
電控工程研究所
;
Institute of Electrical and Control Engineering