Abstract
Doping, compensation and photovoltaic performance have been investigated in all-metal-organic vapour-phase deposition (MOCVD) grown CdTe/CdS solar cells that were co-doped with arsenic and chlorine.
Although arsenic chemical concentration is in the range of 10
17–1.5×10
19
cm
−3, the maximum net acceptor concentration is only in the order of 10
14
cm
−3, as determined by capacitance–voltage characteristics. Admittance spectroscopy revealed shallow traps at 0.055
eV which were attributed to As
Te; its compensation by Cd
i is discussed. Formation of the alloy CdS
x
Te
1−
x
is linked to deep levels at
E
V
+∼0.55
eV and
E
V
+∼0.65
eV. Limits to the diffusion of photo-generated carriers were considered to be important in determining photovoltaic performance rather than carrier lifetime. Prospects for optimizing the performance of such co-doped MOCVD-grown devices are discussed.