Characterization of Primary Carrier Transport Properties of the Light-Harvesting Chalcopyrite Semiconductors CuIn(S_1–xSe_x)₂

Abstract

We report the carrier transport properties of CuIn­(S1–x Se x )2 (0 ≤ x ≤ 1), a promising chalcopyrite semiconductor series for solar water splitting. A low concentration Mg dopant is used to decrease the carrier resistivity through facilitating bulk p-type transport at ambient temperature. Temperature-dependent resistivity measurements reveal a four-order magnitude decrease in bulk electrical resistivity (from 103 to 10–1 Ohm cm) for 1% Mg-doped CuIn­(S1–x Se x )2 as x increases from 0 to 1. Hall effect measurements at room temperature reveal p-type majority carrier concentrations that vary from 1015 to 1018 cm–3 and mobilities of approximately 1–10 cm2 V–1 s–1. These results provide insights into the fundamental carrier transport properties of CuIn­(S1–x Se x )2 and will be of value in optimizing these materials further for photoelectrochemistry applications.

Single-Crystal Growth and Characterization of the Chalcopyrite Semiconductor CuInTe2 for Photoelectrochemical Solar Fuel Production

“…With the resistivity and majority carrier concentration in hand, the mobility (μ) of the p-type carriers was estimated to be 870 cm 2 V −1 s −1 , a startling two orders of magnitude greater than mobilities found for polycrystalline samples of CuInS 2 and CuInSe 2 reported from our lab. 13 Compared to other common light-harvesting semiconductors, this calculated mobility is eight times larger than that of a single crystalline CH 3 NH 3 PbI 3 perovskite (105 cm 2 V −1 s −1 by Hall measurements 34 ) and is 3 orders of magnitude greater than recently reported mobilities of n-type BiVO 4 single crystals measured by Hall measurements, 0.2 cm 2 V −1 s −1 . 35 In the case of halide perovskite materials, the mobility has, at least theoretically, been shown to stem from high band velocities, 36 which are common in perovskite-type materials.…”

“…A reliable linear fit ( R 2 = 0.99) allowed a confident calculation of the hole concentration n p = 1.2 × 10 18 cm –3 . With the resistivity and majority carrier concentration in hand, the mobility (μ) of the p -type carriers was estimated to be 870 cm 2 V –1 s –1 , a startling two orders of magnitude greater than mobilities found for polycrystalline samples of CuInS 2 and CuInSe 2 reported from our lab . Compared to other common light-harvesting semiconductors, this calculated mobility is eight times larger than that of a single crystalline CH 3 NH 3 PbI 3 perovskite (105 cm 2 V –1 s –1 by Hall measurements) and is 3 orders of magnitude greater than recently reported mobilities of n -type BiVO 4 single crystals measured by Hall measurements, 0.2 cm 2 V –1 s –1 .…”

“…For example, by varying the cation ratio M x /M′ y or the anion ratio E n /E′ m , the energetics of the valence and/or the conduction band can be manipulated to shift the absolute energy and position of the band gap. This approach has been used to study water splitting with chalcopyrite variants such as Cu­(In,Ga)­(S,Se) 2 − and CuIn­(S x Se 1– x ) 2 and (Ag x Cu 1– x )­(Ga y In 1– y )­S 2 in our own work. − …”

Observation of [VCu1–Ini2+VCu1–] Defect Triplets in Cu-Deficient CuInS2

“…Polycrystalline Cu 0.99 In 1.00 S 2.00 , (i.e., 1 mol % Cu deficient) was synthesized from the elements Cu (99.99%), In (99.999%), and S (99.99%) in an evacuated quartz tube at T = 1100 °C. 47 After ascertaining the chalcopyrite structure by powder X-ray diffraction (XRD) and composition by EDS, ∼20 g was ground into large grains and sealed under vacuum in a carbon-coated quartz tube. The CuInS 2 single crystal was grown in a vertical Bridgman furnace set to 1140 °C.…”

Identification of interfacial defects in the layered structure of a chalcopyrite compound

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CuInS2 is a diamond-like semiconductor with the crystal structure of chalcopyrite that was first synthesized to explore the applicability to ternary compounds of the Grimm−Sommerfeld valence rules for tetrahedral coordination. [1,2] The chalcopyrites have the diamond-like zincblende structure but with two cations ordered on sublattices. The Bravais lattice of the chalcopyrite is body-centered tetragonal, belonging to space group I4̅ 2d.

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