Effect of GaAs Substrate Micropatterning on Threading Dislocation Density in Solution-Deposited Lead Sulfide Thin Films

Understanding semiconductor growth onto micropatterned substrates, particularly in constrained environments such as trenches with laterally restricted growth areas, becomes crucial, as it can significantly impact lateral diffusion, crystal phase, and structural defect density. Solution deposition of lead sulfide (PbS) thin films on micropatterned GaAs(100) and GaAs(111)A substrates demonstrates that shallow, laterally restricted substrate patterning can strongly affect film morphology, microstructure, and crystalline quality, the latter mainly expressed by threading dislocations. The film thickness and continuity strongly depend on the chemical etching parameters and resulting microfaceting. The threading dislocation density (TDD) was found to decrease with film thickness. The effect of trench width on TDD and film thickness, considering both cluster and ion-by-ion chemical deposition mechanisms, is presented in detail. This research sheds light on the significant role of laterally restricted growth in controlling thin film material quality.