A comparison of the physical properties of CdTe single crystal and thin film

Abstract

Measurements of optical absorption and photoconductivity (steady state, frequency dependent, time dependent) were made on an n-type CdTe single crystal and on an evaporated CdTe thin film. For the single crystal the standard steady state photoconductivity showed an intrinsic peak at 1.4 eV. The lifetime calculated from ac photoconductivity measurements was in the range (1.1 - 5) s. The lifetime showed a minimum at exactly the same photon energy at which the photocurrent was maximum. The decay time was always longer than the lifetime. Optical absorption measurements revealed a direct transition and an optical gap of 1.47 eV at 80 K. Polycrystalline thin films of CdTe were grown by vacuum evaporation on glass substrates held at . The films showed a peak in the spectral distribution () curve at 1.65 eV. Direct and indirect transitions were again observed and found to be temperature dependent.

Photoelectrical properties of (Sb15As30Se55)100−xTex (0⩽x⩽12.5at.%) thin films

“…This figure investigate that, the addition of Tellurium shifts the photocurrent peak into the low-energy side of the spectrum that leads to the decrease in the energy gap. The energy gap (E g ) of (As 30 Sb 15 Se 55 ) 100Àx Te x thin films was calculated by using the relation [10]:…”

Preparation and Characterization of CdSe Single Crystal

“…where ∆σ ac & ∆σ st stand for the alternating and steady state photoconductivity components. The recombination lifetime (τ), was obtained directly from the above curves by drawing a parallel line to the frequency axis at a height of 0.76 of the maximum ∆σ ac / ∆σ st value (tansh 1=0.76) and dropping a normal from the point of intersection to the frequency axis to cut off a segment at 1/4τ [19]. The measured lifetime has very high values (1.3-2.5 ms) indicating that the recombination processes are slowed down through defect centres.…”

Improvement of the electrical properties of Se3Te1 thin films by In additions

“…red shift of the optical band gap. The energy gap (E g ) in In x (Se 3 Te 1 ) 100 − x thin films was calculated by using the relation [34] …”