Title :
Band alignment of CBD deposited Zn(O,S)/Cu(In1−xGax)Se2 interface
Author :
Pankow, Joel W. ; Steirer, K. Xerxes ; Mansfield, Lorelle M. ; Garris, Rebekah L. ; Ramanathan, Kannan ; Teeter, Glenn R.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO, USA
Abstract :
Chemical bath deposition (CBD) Zn(O,S) buffer layers grown on Cu(In1-xGax)Se2 (CIGS) thin films have recently surpassed CdS in high efficiency cells (20.9%). A critical component of a CIGS device is the buffer layer - the layer that is found between the absorber CIGS layer and the ZnO window layer. Although CBD CdS is an effective buffer layer and traditionally used for devices, it is not entirely effective for high bandgap absorber films. The Zn(O,S)/CIGS interface was studied by X-ray photoelectron spectroscopy to reveal the valence band offset (VBO) and conduction band offset (CBO) as -1.15 eV and 1.17 eV respectively. Band bending that accompanies junction formation is also characterized in both layers.
Keywords :
II-VI semiconductors; X-ray photoelectron spectra; buffer layers; conduction bands; copper compounds; energy gap; gallium compounds; indium compounds; interface states; semiconductor thin films; ternary semiconductors; valence bands; wide band gap semiconductors; zinc compounds; Cu(In1-xGax)Se2-ZnOS; X-ray photoelectron spectroscopy; absorber layer; band alignment; band bending; buffer layers; chemical bath deposition; conduction band offset; high-bandgap absorber films; high-efficiency cells; junction formation; thin films; valence band offset; window layer; Buffer layers; Gallium; Photonic band gap; Photovoltaic cells; Substrates; Zinc; buffer layers; copper indium gallium diselenide; zinc oxysulfide;
Conference_Titel :
Photovoltaic Specialist Conference (PVSC), 2014 IEEE 40th
Conference_Location :
Denver, CO
DOI :
10.1109/PVSC.2014.6925240
