Thermally stimulated hall mobility in CdSe single crystals

Abstract

Temperature dependence of Hall mobility in n‐type CdSe single crystals in TSC, thermal quenching of photoconductivity, and equilibrium regimes has been investigated. In the thermally stimulated regime the mobility is considerably larger than the one under equilibrium conditions and reaches the equilibrium value nonmonotonously with increasing temperature. In the case of thermal quenching of photoconductivity a rise of mobility has been observed. The equilibrium mobility for low resistivity samples (ϱ ≈︁10 Ω cm) decreases according to the law μ ∼ T −5/6, and increases exponentially for high resistivity samples (≈︁ 1010 Ω cm). The difficulties of determination of trap parameters by TSC method are discussed in case of strong variation of either mobility or life time due to the recharge of centres. A TSC method based on the mobility measurement in the TSC regime is proposed. The results obtained may be explained by scattering of carriers on clusters. A model explaining the experimentally observed mobility dependence on temperature in the TSC regime is suggested.

Solution-Based Stoichiometric Control over Charge Transport in Nanocrystalline CdSe Devices

“…As stated previously, the mobility values should be considered a conservative estimate (noting that it is the temperature dependence of the mobility and not the precise values that tells the key physics). Indium-doped CdSe NW FETs that were not treated with metal salts show a rise in mobility with decreasing temperature at high temperatures with a ∼ T –0.7 to–0.9 power-law dependence on mobility (although transmission electron microscopy (TEM) images of colloidal CdSe NWs suggest the presence of stacking faults, the energy barriers presented by these imperfections are sufficiently small [Supporting Information Figure S7]), similar to the T –0.5 to–0.83 values − reported for various single crystals of CdSe and typically attributed to bulk acoustic phonons. The mobility plateaus at temperatures below 100 K. This is in contrast to measurements performed on many polycrystalline films, where scattering at grain boundaries and defects give rise to thermally activated transport over the whole temperature range.…”