Composite Zn_1−xCd_xGeAs₂semiconductors: structural and electrical properties

Abstract

We present the studies of structural, transport and magnetotransport properties of [Formula: see text]Cd GeAs crystals with the chemical content changing from 0 to 1. The structural studies indicate that this alloy exists as a composite two-phase material in almost the entire range of average chemical compositions. The two phase nature of our samples does have a significant influence on the carrier transport and magnetotransport of the composite alloy. The change of the conductivity type is observed at room temperature, from p-type for [Formula: see text] to n-type for x > 0.18, respectively. The Hall carrier mobility measured at room temperature decreases as a function of x from about 35 cm (V · s) for the sample with x = 0 down to 3 cm (V · s) for the sample with x = 0.233. For x > 0.233 the Hall carrier mobility shows an increase with x, up to the highest value around 875 cm (V · s) observed for the sample with x = 1. Temperature dependent resistivity measurements indicate the presence of thermal activation of carriers with activation energy, E , with values from 20 to 30 meV for all the studied samples. The temperature dependent Hall effect data show that the grain boundary limited transport is strong in all our samples. For the samples with [Formula: see text] the negative MR is observed at temperatures lower than 100 K and at low magnetic field values, [Formula: see text] T. This effect is interpreted as a weak localization phenomenon with low values of phase coherence length, [Formula: see text] nm.

Splitting of the Chalcopyrite Polyhedron in an Isothermal Zn–Cd–Ge–As Tetrahedron

“…2. To elucidate the experimental data reported by Kilanski et al [1], the 25 at % Ge sections of the Zn 1 -x -Cd x GeAs 2 -Cd 1 -y Zn y GeAs 2 polyhedra (Fig. 2) within the Zn 3 As 2 -Cd 3 As 2 -Ge -As pyramid (Fig.…”

“…Both ternary compounds ZnGeAs 2 and CdGeAs 2 crystallize in the chalcopyrite structure and are united in the phase diagram by a solid solution, which is involved in stable two-phase equilibria with Ge, GeAs, GeAs 2 , As, a (Zn,Cd) 3 As 2 solid solution, and ZnAs 2 -and CdAs 2based limited solid solutions. The polyhedron of a At the same time, according to experimental data [1] the polyhedron is split (Fig. 2) into two ten-vertex heptahedra, and the phase equilibrium between the Zn 1 -x Cd x GeAs 2 and Cd 1 -y Zn y GeAs 2 solid solutions cannot be described in terms of a pseudobinary system in which, at a given temperature, the compositions of phases in solid-solid-vapor equilibrium are fixed.…”

“…ZnGeAs 2 -and CdGeAs 2 -based limited solid solution series were until recently reported [2,3,6,7]. As shown by Kilanski et al in a detailed recent study [1], the solid solution in question exists as a twophase composite throughout the composition range 0 < Zn/Cd < 1 and the unit-cell parameters of both phases increase steadily with increasing Cd content [1].…”

“…The Zn/Cd ratio in (Zn,Cd)GeAs 2 chalcopyrite semiconductors determines their structural and electrical properties [1]. Even though isomorphous, ZnGeAs 2 and CdGeAs 2 form a limited solid solution series [2,3].…”