LOCALIZED PHOTOELECTROCHEMICAL ETCHING WITH MICROMETRIC LATERAL RESOLUTION ON TRANSITION-METAL DISELENIDE PHOTOELECTRODES

The effect of localized photoetching on the photoresponse of n-MoSe2 a nd n-WSe2 single crystal electrodes has been examined with the help of the scanning microscope for semiconductor characterization (SMSC) tec hnique. The SMSC technique has been used to obtain real video images o f the photocurrent response distribution over the semiconductor van de r Waals surface after photoetching. A direct comparison of the photore sponse corresponding to photocorroded and non-photocorroded areas can readily be established from these images. On the basis of various exam ples, it is shown that under moderate depletion conditions of the spac e-charge region, the highest photoresponse always corresponds to photo etched zones. This is unequivocally interpreted as an improvement of t he kinetics of charge transfer at photoattacked compared with non-phot oattacked areas. This trend is always observed whatever the degree of roughness of the photocorroded surface. However, the beneficial effect of photoetching is more persistent on rough (stepped) than on smooth regions.