Photovoltaic Effect and Space Charge Limited Current Analysis in $TlGaTe_2$ Crystals

Anisotropic space charge limited current density analysis and photovoltaic effect in $TlGaTe_2$ single crystals has been investigated. It is shown that, above 330 K, the crystal exhibits intrinsic and extrinsic type of conductivity along (c-axis) and perpendicular (a-axis) to the crystal's axis, respectively. The current density (J) is found to be space charge limited. It is proportional to the square and three halves power of voltage (V) along the a- and c-axis, respectively. Along the a-axis and at sufficiently low electric field values, the activation energy of the current density is found to depend on the one half power of electric field. At high electric fields, the activation energy is field invariant. This behavior is found to be due to the Pool-Frenkel effect and due to a trap set located at 0.26 eV, respectively. Along the c-axis the crystal is observed to operate under the Child-Langmuir space charge limited regime. $TlGaTe_2$ crystals are found to exhibit photovoltaic properties. The open circuit photovoltage is recorded as a function of illumination intensity at room temperature.