Electrical Characterization of Defects in Schottky Au-CdTe:Ga Diodes

Deep electron states in gallium doped CdTe have been studied by deep-level transient spectroscopy method. The Schottky Au-CdTe diodes were processed to perform the investigations. Rectifying properties of diodes have been examined by the room temperature current-voltage and capacitance-voltage measurements. Deep-level transient spectroscopy measurements performed in the range of temperatures 77-350 K yield the presence of three electron traps. The thermal activation energies and apparent capture cross-sections have been determined from related Arrhenius plots. The dominant trap of activation energy $E_2$ = 0.33 eV and capture cross-section σ_2 = 3 × $10^{-15} cm^2$ has been assigned to the gallium related DX center present in the CdTe material

On the Frequency Domain Relaxation Processes in Gallium Doped CdTe and Cd0.99Mn0.01TeCd_{0.99}Mn_{0.01}Te

The dielectric response of gallium doped $Cd_{0.99}Mn_{0.01}Te$ and CdTe alloys possessing DX centers was studied by impedance spectroscopy. Complex modulus and impedance spectroscopic plots were analyzed. Near ideal Debye response of CdTe:Ga was observed, whereas for $Cd_{0.99}Mn_{0.01}Te:Ga$ samples non-Debye behavior was stated. Different relaxation responses may be related to various local atomic configurations in the vicinity of the DX centers in the studied materials

Raman spectroscopy of CdTe/ZnTe quantum dot structures

Semiconductor low-dimensional structures of CdTe quantum dots (QDs) embedded in ZnTe matrix have been investigated by micro-Raman spectroscopy. A reference ZnTe sample (without dots) was also studied for comparison. Both samples were grown by a molecular beam epitaxy technique on the p-type GaAs substrate. The Raman measurements have been performed at room temperature. The samples were excited by an Ar2+ laser of 514.5 nm wavelength. The Raman spectra have been recorded for different acquisition parameters of the measurement. For the reference and QD sample localized longitudinal (LO) phonons of 210 cm–1 wavenumber associated with the ZnTe layer are observed. In the case of QD sample another broadband corresponding to the LO CdTe phonon related to the QD-layer appears at a wavenumber of 160 cm–1. Such behaviour does not exhibit the Raman spectra of the reference sample. Thus the Raman measurements confirm the presence of CdTe layer of quantum dots in the investigated material. Additionally, Raman spectra for both samples exhibit tellurium-related peaks at wavenumbers around 120 cm–1 and 140 cm–1, significantly increasing with laser time exposure. It is shown that the peaks are associated with the formation of Te aggregates on the ZnTe surface due to the laser damage in the ZnTe layer

Electrical Characterization of Defects in Schottky Au-CdTe:Ga Diodes

Deep electron states in gallium doped CdTe have been studied by deep-level transient spectroscopy method. The Schottky Au-CdTe diodes were processed to perform the investigations. Rectifying properties of diodes have been examined by the room temperature current-voltage and capacitance-voltage measurements. Deep-level transient spectroscopy measurements performed in the range of temperatures 77-350 K yield the presence of three electron traps. The thermal activation energies and apparent capture cross-sections have been determined from related Arrhenius plots. The dominant trap of activation energy $E_2$ = 0.33 eV and capture cross-section σ_2 = 3 × $10^{-15} cm^2$ has been assigned to the gallium related DX center present in the CdTe material

Hole Traps in ZnTe with CdTe Quantum Dots

In this study the capacitance-voltage (C-V) and deep level transient spectroscopy measurements have been performed on ZnTe (p-type)-Ti/Al Schottky diodes containing a layer of CdTe self-assembled quantum dots and on the reference diodes without dots for comparison. Both kinds of investigated samples were grown by molecular beam epitaxy technique. The dots were formed during the Stransky-Krastanov growth mode. Comparison of the C-V and deep level transient spectroscopy results obtained for both samples allows us to conclude that the 0.26 eV trap observed exclusively for the QD sample can be assigned to some defects in a wetting layer or CdTe/ZnTe interface

Capacitance-Voltage Studies of Ti/p-ZnTe Schottky Barrier Structures Containing CdTe Quantum Dots

In this paper the electronic states of self-organized CdTe quantum dots embedded in ZnTe matrix are studied by means of capacitance-voltage (C-V) characteristics within the temperature range of 180-300 K. A reference diode of the same layer structure but without quantum dots is studied also for comparison. The C-V characteristics measured for the reference diode exhibit bulk behaviour in contrast to the quantum dots sample for which a characteristic step corresponding to discharging of quantum dots is clearly visible within broad range of temperatures. A quasistatic model based on the self-consistent solution of the Poisson equations is used to simulate the capacitance. By comparison the calculated C-V curve with experimental curve the apparent thermal activation energy for hole emission from the quantum dots to the ZnTe matrix is found to be equal to (0.12 ± 0.03) eV