Abstract
The nano-crystalline PbS/
n-Si heterostructure was studied using photocurrent spectra,
I–
V and
C–
V characteristics and admittance spectroscopy. The frequency dependent junction capacitance and conductance measurements show the presence of two contributions: first, a defect related mechanism which we attribute to a deep trap level with a large cross-section in nano-crystals with smaller sizes around 5
nm at the interface with Si and a second mechanism with an activation energy of about 250
meV, attributed to carrier transport in relatively large PbS grains of about 15
nm in size.