Trap-Assisted Switching in Silicon Nanocrystal Based p-i-n Device

An all Si, p-i-n device, consisting of a nanostructured porous Si layer sandwiched between a p-type crystalline Si and an n-type amorphous Si, exhibits current controlled switching. Temperature-dependent charge transport characteristics of the device reveal that trapping and detrapping of injected carriers at the interface of nanocrystalline Si core and the oxide shell, through impact excitation, are responsible for the observed switching. The abundance of surface inhomogeneities in the form of sub-oxides and dangling bonds creates multiple charge trapping centers which, in turn, endow the device with switching characteristics. The density of trap states ( $ \sim 10^{11}$ /cm $^{2}$ ) estimated from the detrapping potential is in very good agreement with the trap density obtained directly from C-V measurements.