Evolution of the amount of InAs in wetting layers in an InAs/GaAs quantum-dot system studied by reflectance difference spectroscopy
Chen, Y H; Jin, P; Liang, L Y; Ye, X L; Wang, Z G; Martinez, Arturo I; Chen, Y H; Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People’s Republic of China; Jin, P; Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People’s Republic of China; Liang, L Y; Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People’s Republic of China; Ye, X L; Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People’s Republic of China; Wang, Z G; Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People’s Republic of China; Martinez, Arturo I; Institute of Physics, National Autonomous University of Mexico, Mexico City, Mexico
Журнал:
Nanotechnology
Дата:
2006-05-14
Аннотация:
The wetting layer (WL) in InAs/GaAs quantum-dot systems has been studied by reflectance difference spectroscopy (RDS). Two structures related to the heavy-hole (HH) and light-hole (LH) related transitions in the WL have been observed. On the basis of a calculation model that takes into account the segregation effect and exciton binding energies, the amount of InAs in the WL (t<sub>WL</sub>) and its segregation coefficient (R) have been determined from the HH and LH transition energies. The evolutions of t<sub>WL</sub> and R exhibit a close relation to the growth modes. Before the formation of InAs dots, t<sub>WL</sub> increases linearly from ∼1 to ∼1.6 monolayer (ML), while R increases almost linearly from ∼0.8 to ∼0.85. After the onset of dot formation, t<sub>WL</sub> is saturated at ∼1.6 ML and R decreases slightly from 0.85 to 0.825. The variation of t<sub>WL</sub> can be interpreted by using an equilibrium model. Different variations of in-plane optical anisotropy before and after dot formation have been observed.
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