ABSTRACT
Recently, a novel growth technique has been demonstrated that involves 90° interfacial mis„t (IMF) arrays formed during the growth of AlSb on Si (001) (Balakrishnan et al. 2005). ese IMF arrays can relieve 99% of the entire strain caused by the 13% lattice mismatch via a self-assembled two-dimensional (2D) array of 90° dislocations without using a very thick MB. e IMF arrays have been reported in several systems including GaP/Si (Kawanami et al. 1982), GaAs (or AlGaAs)/Si (Wang 1984), InAs/GaAs (Trampert et al. 1995), InAs/GaP (Chang et al. 1996), GaSb/GaAs (Rocher 1991), and InP/GaAs (Jin-Phillipp
et al. 2001), besides AlSb/Si (Kim et al. 2006) over a range of lattice-mismatched conditions ranging from ∆ao/ao= 0.4% (GaP/ Si) to ∆ao/ao= 13% (AlSb/Si). e IMF array forms at the III-V/ Si interface and remains localized within that plane rather than propagating vertically into the material. erefore, the IMF array immediately accommodates the hetero-interface strain by the bending and stretching of atomic bonds surrounding each 90° dislocation. It is noted that the 90° dislocation threads neither vertically nor laterally. A detailed explanation of the IMF formation via atomic self assembly and energy minimization has been reported (Jallipalli et al. 2007). e IMF growth mode on Si (001) results in low-defect density bulk epitaxy (~106/cm2) that has enabled optically pumped VCSELs and superluminescent diodes (Balakrishnan et al. 2006a) In addition, the growth of AlSb on Si o›ers signi„cantly better agreement of the substrate and epilayer thermal expansion coe¢cients compared to GaAs on Si (Kumar and Sastry 2001). At 300 K, AlSb has a thermal expansion coe¢cient of 2.55 × 10−6/K, which is very close to that of Si (2.59 × 10−6/K). In comparison, the thermal expansion coef-„cient of GaAs is 6.93 × 10−6/K, resulting in a signi„cant tensile strain during cooling down from the growth temperature to RT. However, there still remains a substantial issue of the formation of antiphase domains (APDs) that have inhibited the realization of laser diodes on Si (001) substrates.
