Temperature dependent electrical behaviour of Cu2SnS3 films

Abstract

The temperature dependent electrical properties of the dropcasted Cu2SnS3 films have been measured in the temperature range 140 K to 317 K. The log I versus √V plot shows two regions. The region at lower bias is due to electrode limited Schottky emission and the higher bias region is due to bulk limited Poole Frenkel emission. The ideality factor is calculated from the ln I versus V plot for different temperatures fitted with the thermionic emission model and is found to vary from 6.05 eV to 12.23 eV. This large value is attributed to the presence of defects or amorphous layer at the Ag / Cu2SnS3 interface. From the Richardson's plot the Richardson's constant and the barrier height were calculated. Owing to the inhomogeneity in the barrier heights, the Richardson's constant and the barrier height were also calculated from the modified Richardson's plot. The I-V-T curves were also fitted using the thermionic field emission model. The barrier heights were found to be higher than those calculated using thermionic emission model. From the fit of the I-V-T curves to the field emission model, field emission was seen to dominate in the low temperature range of 140 K to 177 K. The temperature dependent current graphs show two regions of different mechanisms. The log I versus 1000/T plot gives activation energies Ea1 = 0.367095 − 0.257682 eV and Ea2 = 0.038416 − 0.042452 eV. The log (I/T2) versus 1000/T graph gives trap depths Φo1 = 0.314159 − 0.204752 eV and Φo2 = 0.007425 − 0.011163 eV. With increasing voltage the activation energy Ea1 and the trap depth Φo1 decrease. From the ln (IT1/2) versus 1/T1/4 graph, the low temperature region is due to variable range hopping mechanism and the high temperature region is due to thermionic emission.

Structural properties and variable-range hopping conductivity of Cu2SnS3

“…The ternary compound Cu 2 SnS 3 (CTS) is one of the promising candidates as an absorbent layer of solar cells, due to its environmentally friendly elemental composition, low cost and prevalence in nature, as well as their suitable optoelectronic properties. Many studies have shown that Cu 2 SnS 3 is a p-type semiconductor that crystallizes in different syngonies (tetragonal, cubic, monoclinic, triclinic) [1][2][3][4][5]. The band gap of CTS has been reported to be in the range of 0.93-1.51 eV, depending on its crystal structure [1-3, 6, 7].…”

Vibrational properties of the mechanochemically synthesized Cu2SnS3: Raman study

“…Since the characteristic wavenumber of cubic CTS phase is 303 cm −1 , we conclude that mode at 307 cm −1 is result of a co‐existence of the orthorhombic and the cubic polymorphs. [ 3,41,55 ] Neither spectra demonstrates presence of modes at 163 and 221 cm −1 corresponding to Sn–S binary phases, which indicate that after 10min milling time the SnS binary phases completely disappears. Also in neither spectra the mode at 475 cm −1 that corresponds to A 1 (LO) mode of CuS is registered.…”

“…[ 4 ] For the tetragonal CTS (t‐CTS) there are 29 Raman active modes represented as 2A 1 + 3B 1 + 6B 2 + 9E. [ 41 ] In the case of the cubic structure (c‐CTS) one triple degenerated Raman active mode is predicted. This mode is also infrared active, which leading to their LO–TO splitting.…”

Electrical Properties of Compact Drop-Casted Cu2SnS3 Films

“…Films with smooth, compact, and homogeneous surface have higher conductivity and mobility with lower carrier concentration; however, rough and porous films have comparatively low conductivity and mobility. [14][15][16] The above discussion reveals that most authors [10][11][12] have reported TDEC of CTS films below 300 K while reports above 300 K are very few. 17 Solar cells usually operate above 300 K, and hence it is important to study their electrical properties above 300 K. Brus et al (Ref.…”