ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The effect of polyiodide solution treatment on WSe2−both n and p type−prior to Schottky junction formation, has been studied. The junctions have been characterized mainly by (photo)current/voltage and spectral response measurements. Barrier heights of (approximately-greater-than)1 V have been found [Eg(WSe2)∼1.2 eV]. X-ray photoelectron spectroscopy and Rutherford backscattering analyses of polyiodide-treated WSe2 show that some iodine species (the nature of which has not been conclusively identified) exists to considerable depths (10−6–10−5 cm) in the WSe2, and that the I uptake is much faster and more extensive on defects ((parallel)c faces) than on the van der Waals (⊥ c) face, if indeed it is adsorbed on the latter at all. Also, the surface charge differs between the two faces for both the nontreated and I-treated cases. The results are consistent with a passivation mechanism whereby some I species at the defects chemically attack the deposited metal (Au,Al), effectively removing the metal/defect–semiconductor junctions which short the good diode behavior of the greater part of the surface. The main effect of the defects is to decrease the photovoltage by increasing the dark forward current. The assignment of these defects as recombination centers, as is usually believed to be their main effect on these photovoltaic cells, while often (though not always) important, is secondary to their effect on the dark forward current.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.350609
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