Method of fabricating diode structure

A method of manufacturing a diode structure includes forming a first stack on a silicon layer on a substrate. A first sidewall spacer extending along and covering a sidewall of the first stack is formed. The silicon layer is selectively etched to a first predetermined depth, thereby forming a second stack. The remaining silicon layer includes a silicon base. A second sidewall spacer extending along and covering a sidewall of the second stack is formed. The silicon base is selectively etched to form a third stack on the substrate. With the second sidewall spacer as a mask, lateral plasma ion implantation is performed. Defects at the interface between two adjacent semiconductor layers can be reduced by the method.