Materials Science and Engineering B77 (2000) 83 – 87 Evaluations of strains in fused layers using patterned substrates Sung Min Hwang a,b, *, Ju Young Lee a , Se-Ki Park a , Chan Kyeong Hyon a , Yong Kim c , Young Ju Park a , Eun Kyu Kim a , In-Hoon Choi b a Semiconductor Materials Laboratory, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130 -650, South Korea b Department of Materials Science, Korea Uniersity, 1 Anam-Dong, Sungbuk -Ku, Seoul 132 -701, South Korea c Department of Physics, Dong -A Uniersity, Pusan 604 -714, South Korea Received 13 March 2000; accepted 19 April 2000 Abstract Strains existed in wafer fused AlGaAs/GaAs quantum wells on patterned InP substrate was systematically evaluated. The fused layers on the U-grooved substrate were characterized by scanning electron microscopy and micro-photoluminescence. Through the micro-probing technique, we observed no misfit-strain in the wafer fused interface layer but a little bit of thermal strain resulted from different thermal expansion coefficients in between GaAs and InP matrices. We successfully proved that the concept of strains existed in wafer fused layers by employing the patterned substrates. © 2000 Elsevier Science S.A. All rights reserved. Keywords: Micro-PL; Wafer fusion; Epitaxy www.elsevier.com/locate/mseb 1. Introduction The integration of multiple device elements in III – V material system has been studied vigorously in recent years and the integrated devices will be in demand more and more in the near future [1,2]. It further allows grown single crystal layers to be transferred and monolithically integrated onto a substrate of a different lattice parameter or of a different crystal orientation to fabricate novel optoelectronic devices. However, because of lattice mismatch, combining two different semiconductors is so hard that device fabrica- tion is frequently restricted by those problems. On the other hand, wafer fusion is considered to be a promis- ing technique to bond two different semiconductor materials through overcoming the lattice mismatch problems. However, there are some strains exist near the fused interface layer [3]. It is necessary to understand the electrical and optical properties of the interface and fused layer in conjunction with clarifying the strains. In particular, the modification of the electronic energy band structure due to the strains has significant impli- cations for device applications. Several groups have obtained high resolution transmission electron mi- croscopy cross sectional views of the GaAs/InP fused interface and have observed an array of misfit disloca- tions along the interface with a regular spacing as expected from the amount of lattice mismatch [4], which was estimated by the current – voltage curve of n – n or p – p junctions [5,6]. Other groups have studied the strain field near the bonded interface by using numerical methods [7]. In this work, we have investigated the strains existed in the wafer fused layers between GaAs and InP. We found that only a thermal strain existed in the fused layer. In other to confirm the strain accurately, we considered several possibilities such as intermixing and strains resulted from lattice mismatches and different thermal expansion coefficients, respectively. Particularly, wafer fusion was performed by using patterned substrates to elucidate the origin of strains existed in patterned and unpatterned regions. We also compared the influences of twisted bonding method on strains to confirm it. * Corresponding author. Fax: +82-2-9585739. E-mail address: hsm@kistmail.kist.re.kr (S.M. Hwang). 0921-5107/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved. PII:S0921-5107(00)00468-2