flat-band potential (Vfb)
and carrier concentration (ND)
were calculated from the X-axis intercept and the slope of the linear fit of
the Mott–Schottky equation i,ii;
where e is
the electron charge, ? (= 8.5) is the
dielectric constant, ?0 is
the permittivity in vacuum iii.
The Mott–Schottky plots (not shown) confirm the n-type behavior of all the
fabricated Cd1?xZnxS thin films. The ND values for all the deposited films were calculated
and are tabulated in Table 2. It can be seen from the Table 2, all the Zn incorporated
samples shows higher ND and
Vfb values compared to
untreated CdS while sample Z-3 appears to have a higher ND with respect to the other fabricated CdS films along
with the highest Vfb value
(Fig. 1 and Table 2). The Vfb
value was found to be tunable with the Zn2+ concentration in the
reaction solution. The existence of different Vfb in a same PEC indicates change in relative band edge
position supports of the fabricated Cd1-xZnxS along with
the Zn2+ concentration. The tunability of the relative band edge position suggests the
possibility of obtaining smooth band lineup throughout the p-n junction 19.
These variations in ND and Vfb affect both short circuit current (ISC) and open circuit voltage (VOC) value of the fabricated Cd1-xZnxS
i M. Akif
Shikhan Aliyev and M. El-rouby, Int. J. Thin Film. Sci. Technol. 2, (2013)
ii W. G. C. Kumarage, L. B. D. R. P. Wijesundara, V. A.
Seneviratne, C. P. Jayalath, and B. S.
Dassanayake, Semicond. Sci. Technol. 32
(2017) 045014 (11pp)
iii D. Johnson
and M. Sadeghi, J. Mater, 7, (1996)
iv W. G. C.
Kumarage, L. B. D. R. P. Wijesundara, V. A. Seneviratne, C. P. Jayalath, and B. S. Dassanayake, Procedia Eng. 139, (2016)