Characterizations of Ga-Doped Cu_1.75Zn(Sn_1−xGa_x)Se₄Bulks

Abstract

p-type Ga-doped Cu1.75ZnSn1−xGaxSe4(x = 0–0.6) bulks were prepared by a liquid−phase reactive sintering method at 600°C with soluble sintering aids of Sb2S3 and Te. Defect physics and chemistry were studied by measuring electrical properties of Ga-doped CZTSe as a function of dopant concentration. With the value x increasing from 0 to 0.6, the carrier concentration increased from 1017 to 1019 cm−3, but the hole mobility greatly enhanced from 1.23 to a maximum value of 8.6 cm2 V−1 s−1 then decreased to about 1.23 cm2 V−1 s−1 at x = 0.6. The largely increased carrier concentration and the slightly changed lattice parameters for Ga-CZTSe with increasing the Ga content are related to the types of its defects. Ga-CZTSe at x = 0.4 with carrier concentration of 8.9 × 1018 cm−3 showed the highest mobility of around 8.6 cm2 V−1 s−1. This result may provide a guide to fabricate a potential absorber for thin-film solar cells through further optimization in Cu-Zn-Sn-Se system.

Microstrain effects of laser-ablated Au nanoparticles in enhancing CZTS-based 1 Sun photodetector devices

“…29,30 However, since the density of AuNPs in AuNPs@CZTS(1) was excessive compared to the thickness of CZTS(1) thin film, and the intensity of the prominent peak in the (112) direction that is weakened by occupying the unsuitable voids in the crystal structure. [31][32][33] Since the thin film of CZTS(2) was thicker, the density of AuNPs did not adversely affect its crystal structure; on the contrary, the density of the main peak was enhanced.…”

Carrier Transport Properties

“…The decrease in the unit cell size of the host crystal with increasing dopant concentration was observed in the Al-and Ga-doped CZTSe samples [65,66], whereas the increased unit cell size was observed in the In-doped sample [67]. These facts indicate that the doped group III [64] (open circles).…”

“…These measurements were performed on Cu-deficient CZTS [43], Cu-deficient CZTSe [59], Cu-deficient and Zn-rich CZTSe [60], Cu-rich CZTSe [61], Cu-deficient/Cu-rich CZTSe [62], Cu-deficient and Sn-rich CZTSe [63], and Cudeficient CZTSSe [64]. Note that such CZTSe-based crystals investigated by Kuo et al [59][60][61][62][63][64][65][66][67][68] were synthesized by reactive liquid-phase sintering at 600 C for 2 h with the help of sintering aids of Sb 2 S 3 and Te. These crystals were Cu 1.75 Zn(Al x Sn 1−x )Se 4 with x = 0-0.6 [65], Cu 1.75 Zn(Ga x Sn 1−x )Se 4 with x = 0-0.6 [66], Cu 1.75 Zn(In x Sn 1−x )Se 4 with x = 0-0.6 [67], and (Cu 2−x Mg x )ZnSnSe 4 with x = 0-0.4 [68].…”

“…Effects of foreign atom doping into CZTSe crystals on the electrical transport properties were investigated by Kuo et al [65][66][67][68]. Results obtained from these authors are summarized in Figure 7.16.…”

“…The shaded region corresponds to that exhibiting n-type conductivity. In Figure 7 [65], for (b) Cu 1.75 Zn(Ga x Sn 1−x )Se 4 from Kuo and Tsega [66], for (c) Cu 2 Zn(In x Sn 1−x )Se 4 from Kuo and Tsega [67], and for (d) (Mg x Cu 2−x )ZnSnSe 4 from Kuo and Wubet [68]. The fact teaches that the acceptor states newly formed by introducing the group III foreign atoms into CZTSe are not of simple impurity states.…”