The Growth of High Quality GaAs Epilayers on Stripe Patterned InP Substrates With a Transferred GaAs Fused Layer
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exist problems in this method such as screw dislocations resulted from twist bonding, oxide and organic contaminations and so on, at the interface. On the other hand, epitaxial growth on patterned compound semiconductor substrates has been studied extensively because it is very useful for obtaining novel structures to realize new and/or superior properties of optoelectronic devices. The lateral growth rate change of the epitaxial layers on nonplanar GaAs substrate has been studied for the patterned wafers in micrometer scale [9]. The growth conditions are affected by the following mechanisms. The first one is that the growth rate is greatly affected by the surface geometry of the substrate [6]. The other one is the surface migration of adatoms from a crystal plane to another [7]. Therefore, the growth behavior for specific crystal planes should be investigated to prepare a high quality epitaxial layer and then fabricate quantum wires(QWRs) on a transferred GaAs fused layer. In particular, QWR's grown by metal organic chemical vapor deposition (MOCVD) on non-planar substrates have been widely studied because the size and the shape of QWR with damage free interface can easily be controlled by the patterning of substrate and optimized growth condition. In our previous report [8], we have fabricated the AlGaAs/GaAs quantum well wire laser using current blacking layers for current confinement on GaAs substrates. Also, we reported the lateral growth enhancement on patterned GaAs substrate [9]. In this work, we propose a new method for the formation of high quality epitaxial layers through both the techniques of wafer fusion and subsequent patternings. We have successfully formed a GaAs QWR on the patterned GaAs fusion layer on InP substrate.
71 Mat. Res. Soc. Symp. Proc. Vol. 618 © 2000 Materials Research Society
The proposed method shows unique growth behavior on patterned fusion layers from which the QWRs can be formed with little difficulty for both [0'l ] and [0111 directions. EXPERIMENT An atmospheric pressure metal organic chemical vapor-phase deposition (AP-MOCVD) system was used for the growth of the epitaxial layers. 1.5 ,n thick GaAs epilayers were grown on semi-insulating (100) GaAs substrates followed by 100 nm thick AlAs layers. After contacting the mirror faces of both InP and GaAs in-phase, they were then loaded into an electric furnace. A pressure of 500 g/cm 2 was applied to both wafers using a molybdenum block maintained at 550t for 30 minutes in H2 ambient. Heating and cooling rates were 101C/min and 2*C//min, respectively. The GaAs substrates were lifted off from the InP substrate in a dilute HF solution for 24 hours through the removal of the AlAs layer. A patterned InP substrate was prepared by striped patterning along the direction followed by photolithography and chemical wet etching. The chemical etchant of 1H2SO 4 : 8H 20 2 : 40H20 was utilized for the selective etching of GaAs layer only. The widths of the patterned region were approximately 5 jan and the inter-distance of pattern-to-pattern
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