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ABSTRACT: High‐resolution x‐ray analysis of Si delta‐doped GaAs grown by molecular‐beam epitaxy at a low substrate temperature (230 °C) is presented. Superlattice satellite peaks in the rocking curve are observed for the sample annealed at 700 °C for 10 min. The peak intensity increases with increasing postgrowth annealing temperature and reaches the maximum value for the 900 °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.
Applied Physics Letters 07/1994; · 3.84 Impact Factor
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ABSTRACT: Low temperature (LT) GaAs delta doped with In and Al have been grown by molecular beam epitaxy and annealed at 600–900 °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‐Al 0.25 Ga 0.75 As 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.
Applied Physics Letters 06/1994; · 3.84 Impact Factor
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ABSTRACT: Low temperature InGaAs strained quantum wells have been grown by molecular beam epitaxy and annealed at 600–900 °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.
Applied Physics Letters 04/1994; · 3.84 Impact Factor
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ABSTRACT: Strong enhancement in the luminescence intensity is observed in Al 0.22 Ga 0.78 As epitaxial layers grown on misoriented (111)B GaAs at 630 °C. For 3° 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) Al 0.4 Ga 0.6 As/GaAs quantum well laser diode structures grown under identical conditions with a low threshold current density of 150 A/cm<sup>2</sup> are indications of excellent AlGaAs material quality. Electron mobility for 3° misoriented (111) Al 0.25 Ga 0.75 As 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.
Applied Physics Letters 11/1993; · 3.84 Impact Factor
