Characterization and Suppression of Anti-Phase-Boundary Defects in GA-AS-ON-SI Films Using SHG and Aspect-Ratio-Trapping

The semiconductor industry is exploring hetero-epitaxial growth of III-V semiconductors on Si substrates as a way to marry the superior optical properties and high carrier mobility of III-V semiconductors to the established low-cost, high-volume Si platform for electro-optic, solar cell, and high-performance electronics applications. The dominant technical challenge is the III-V film's tendency to form ``anti-phase domains'' (APDs) --- $i.e. $areas of 0.1 to 1 micron lateral size in which polar Ga-As bonds are inverted in neighboring domains, resulting in undesirable Ga-Ga and As-As bonds at the anti-phase boundaries (APBs). To evaluate strategies for suppressing them, a strong need exists for fast, non-destructive methods of detecting APBs that distinguish them from other defects ($e.g$. threading dislocations, or TDs). Here we show that optical SHG characterizes APDs sensitively, selectively and non-invasively. Using SHG as an APD monitor, we then show that growing the GaAs film on a Si substrate patterned with SiO$_{2}$ trenches -- a strategy originally designed to trap TDs -- can also dramatically suppress APDs. While molecular mechanisms by which ``aspect-ratio trapping'' (ART) suppresses APDs are not yet clear, the high-throughput SHG diagnostic enables unprecedented freedom in exploring effective trench pattern designs