While ideal semiconductors are characterized by an energy gap that separates filled and empty electronic states, real semiconductors have defects that produce new energy levels within the gap.  These defect-related levels trap charge carriers and reduce the efficiency of solar cells.  With transient capacitance spectroscopy (also known as deep level transient spectroscopy or DLTS), we selectively fills these levels and then monitor their occupation to evaluate capture characteristics, depth, and density.  The paper below describes a unique trap that we discovered with DLTS.

 

(Click on the link below to download and view PDF file)

 

Observation of an anomalous minority carrier trap in n-type InGaAs

Tim Gfroerer and Kiril Simov

Department of Physics, Davidson College, Davidson, NC 28035

Mark Wanlass

National Renewable Energy Laboratory, Golden, CO 80401

in 

Indium Phosphide and Related Materials

(edited by Iain Thayne, John Marsh, and Catrina Bryce, IEEE, 2005)