Transport and recombination kinetics in TlGaTe₂ crystals

Abstract

In this work, the transport and recombination mechanisms as well as the average hole‐relaxation time in TlGaTe2 have been investigated by means of temperature‐dependent dark electrical conductivity, photoexcitation intensity‐dependent photoconductivity, and Hall effect measurements, respectively. The experimental data analysis revealed the existence of a critical temperature of 150 K. At this temperature, the transport mechanism is disturbed. The dark conductivity data analysis allowed the determination of an energy state of 258 meV. The hole‐relaxation time that was determined from the Hall mobility data was observed to increase with decreasing temperature. The behavior was attributed to the hole–thermal lattice scattering interactions. At fixed photoexcitation intensity, the photocurrent Iph decreases with decreasing temperature down to 150 K. Below this temperature it changes direction. The latter data allowed the determination of the recombination center energy as 110 meV. On the other hand, at fixed temperature and variable illumination intensity, the photocurrent follows the relation IphαFn (the value of the exponent, n, decreases with decreasing temperature).

First-Principle Calculation of High Absorption-TlGaTe2 for Photovoltaic Application

“…For the indirect electronic transition, we found that the effective mass of electrons is 0.196 me (me–a mass of an electron) along the M|X-P direction and the effective mass of holes is 0.736 me along the Z1-M direction. It is interesting to note that Qasrawi et al used the Hall effect measurement and reported the hole effective mass of TlGaTe 2 to be 0.730 me [7], which is in good agreement with our calculated hole effective mass (0.736 me). For the direct transition, we noted that the EM of electrons is 0.378 me and EM of holes is 0.736 me at Z-point.…”

“…Thallium-bearing ternary materials have been studied in optoelectronics [5], but not extensively investigated in photovoltaics due to the fact that thallium is toxic. Researchers have shown interest to the Hall effect analysis, the photoconductivity and recombination kinetics in dichalcogenide-TlGaTe 2 material [6,7]. From our earlier study on non-silicon solar cell materials [8], we identified that TlGaTe 2 has a strong absorption coefficient in the visible region, but a complete study of TlGaTe 2 is needed to confirm that it is potential material for PV applications.…”

Photovoltaic Effect and Space Charge Limited Current Analysis in TlGaTe2Crystals

“…The value of the trap energy level being 0.26 eV which was determined from the J−V plots of the a-axis measurement coincides with that determined from (the ohmic region measurements) resistivity analysis along the c-axis [10]. In spite of the pronounced anisotropy of the crystal, the same energy levels appears to exist along both directions, it only diers in the temperature domination region.…”

“….20 cm, ϵ s = 14.8 [16], g = 2 which are reported in the previous works [9,10], the hole trap density values were calculated at room temperature from Eq. (4) and found to be 5.6 × 10 10 cm −3 .…”

“…In our previous works we have reported the Hall eect analysis [9] and the photoconductivity and recombination * corresponding author; e-mail: aqasrawi@atilim.edu.tr kinetics [10] in TlGaTe 2 crystals. The Hall eect analysis revealed a carrier eective mass, an acceptor and donor concentrations of 0.73m 0 , 4.10 × 10 17 cm −3 and 1.20 × 10 17 cm −3 , respectively.…”