Detection of electron emission as DLTS signal in CdTe solar cells

This work identifies an incongruity in the detection of the minority carrier signal in CdTe solar cells during the deep level transient spectroscopy (DLTS) measurement. Use of quasi-Fermi level instead of Fermi level of majority carriers to estimate the probability of emitting carriers seems to correct the ambiguity. During the experiment, signals from minority carrier traps (electron traps) were detected by using a long filling pulse time instead of an electron injection pulse. The DLTS measurements of CdTe solar cells observed a single electron trap with energy level EE1 = 0.47 eV, and two hole traps with energy levels, EH1 = 0.17 eV and EH2 = 0.27 eV. The possibility of any impact from the back contact was excluded, and the phenomenon was clarified by the simulation. It was further observed that when the condition of quasi-Fermi level is considered, the results of calculated probability were significantly different from that of the results that used only Fermi level of majority carriers. The simulation...

[1]  K. Chin,et al.  Semiconductor steady state defect effective Fermi level and deep level transient spectroscopy depth profiling , 2016 .

[2]  Martin A. Green,et al.  Solar cell efficiency tables (version 48) , 2016 .

[3]  M. Topič,et al.  Status and Potential of CdTe Solar-Cell Efficiency , 2015, IEEE Journal of Photovoltaics.

[4]  K. Durose,et al.  A low-cost non-toxic post-growth activation step for CdTe solar cells , 2014, Nature.

[5]  K. Chin,et al.  Steady state minority carrier lifetime and defect level occupation in thin film CdTe solar cells , 2014 .

[6]  I. Sankin,et al.  CdTe Solar Cells at the Threshold to 20% Efficiency , 2013, IEEE Journal of Photovoltaics.

[7]  Artur Vicente Pfeifer Coelho,et al.  Distinguishing bulk traps and interface states in deep-level transient spectroscopy , 2011 .

[8]  M. Burgelman,et al.  Signature of a back contact barrier in DLTS spectra , 2011 .

[9]  L. Bing,et al.  Deep level transient spectroscopy investigation of deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact , 2010 .

[10]  Arturo Morales-Acevedo,et al.  Thin film CdS/CdTe solar cells: Research perspectives , 2006 .

[11]  S. Kurtz,et al.  Observed trapping of minority-carrier electrons in p-type GaAsN during deep-level transient spectroscopy measurement , 2005 .

[12]  M. Burgelman,et al.  Characterization of deep defects in CdS/CdTe thin film solar cells using deep level transient spectroscopy , 2003 .

[13]  C. Ferekides,et al.  The effect of the CdCl2 treatment on CdTe/CdS thin film solar cells studied using deep level transient spectroscopy , 2003 .

[14]  Su-Huai Wei,et al.  Chemical trends of defect formation and doping limit in II-VI semiconductors: The case of CdTe , 2002 .

[15]  F. Hasoon,et al.  Deep-level impurities in CdTe/CdS thin-film solar cells , 2000 .

[16]  G. Müller‐vogt,et al.  Investigations on the effect of contacts on p-type CdTe DLTS-measurements , 1999 .

[17]  Beatrice Fraboni,et al.  Deep energy levels in CdTe and CdZnTe , 1998 .

[18]  D. Bonnet,et al.  Deep level transient spectroscopy of CdS/CdTe thin film solar cells , 1997 .

[19]  J. Szatkowski,et al.  Deep-level transient spectroscopy study of hole traps in p-type CdTe , 1994 .

[20]  H. Nakashima,et al.  Method of Analysis of a Single-Peak DLTS spectrum with Two Overlapping Deep-Trap Responses , 1986 .

[21]  I. Thurzo,et al.  On the Role of the Back Contact in DLTS Experiments with Schottky Diodes , 1985, June 16.

[22]  N. M. Johnson,et al.  Transient capacitance measurements of hole emission from interface states in MOS structures , 1977 .

[23]  D. Lang.  Deep‐level transient spectroscopy: A new method to characterize traps in semiconductors , 1974 .

[24]  W. Read,et al.  Statistics of the Recombinations of Holes and Electrons , 1952 .

[25]  Kimiyoshi Yamasaki,et al.  Deep Level Transient Spectroscopy of Bulk Traps and Interface States in Si MOS Diodes , 1979 .