Influence of oxidation on the transport properties of IV–VI-thin films

Size Effects in Transport Properties of PbSe Thin Films

“…During the last 15 years approximately, we have carried out a cycle of experimental studies [12][13][14][15][16][17][18][19][20][21][22] of the room-temperature dependences of r, S, the Hall coefficient R H , and Hall charge carrier mobility l H on the PbSe layer thickness (QW width) in PbSebased QWs and SLs. The initial materials used for growing single PbSe layers were lead selenide crystals with different charge carrier types and concentrations: (1) stoichiometric p-PbSe crystals with p = 3 9 10 18 cm À3 , 14 (2) nonstoichiometric n-PbSe crystals with n = 3 9 10 18 cm À3 , 15-17 and (3) n-PbSe crystals heavily doped with PbCl 2 (n = 3 9 10 20 cm À3 ).…”

Room-temperature oxygen sensitization in highly textured, nanocrystalline PbTe films: A mechanistic study

“…7,8 Oxidation annealing is known to incorporate oxygen in the film and sensitize the infrared photoresponse of lead chalcogenide. 5,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Oxygen can introduce gap states which deplete electrons and result in spatial separation of carriers, thus increasing the photogenerated carrier lifetime, and enhancing photoconductivity. Some key findings are: (1) polycrystalline lead chalcogenide films evaporated from stoichiometric bulk are usually n-type due to the poor sticking coefficient of chalcogen atoms and hence chalcogen deficiency.…”

“…Some key findings are: (1) polycrystalline lead chalcogenide films evaporated from stoichiometric bulk are usually n-type due to the poor sticking coefficient of chalcogen atoms and hence chalcogen deficiency. After sensitization, oxygen introduces gap states which can deplete electrons from the conduction band; (2) oxygen-sensitized films exhibit p-type conduction, increased film resistivity and very long photogenerated carrier lifetime; (3) oxygen sensitization is a diffusion-limited process; 17,[20][21][22][23][24] (4) grain boundaries assist in oxygen diffusion, as oxygen sensitization in polycrystalline films occurs over a much shorter time scale compared to their single-crystalline counterparts; [15][16][17] and (5) solutiondeposited PbSe films used in commercial IR detectors often exhibit high sheet resistance (10 5 À10 6 X), but reports on the actual carrier concentrations in these films are scarce.…”

Hydrothermal synthesis of nano-sized AgPb18SbTe20 thermoelectric powders

“…Moreover, it is convenient to prepare thermoelectric devices using PbTe-based materials because PbTe can be made n-or p-type semiconductor by slightly changing its stoichiometry (Pb-rich PbTe is n-type, while Te-rich PbTe is p-type), or by introducing some impurities to the matrix [4,5]. The presence of an oxidized layer on the PbTe or PbS film surface causes a strong thickness dependence of the thermoelectric properties, including inversion of the carrier sign from n to p [6,7].…”

“…Many efforts have been carried out to improve their thermoelectric energy conversion efficiency by changing their microstructures [6,8], by alloying with other elements [9][10][11] or by making the materials nano-sized, such as thin-film structures, superlattice structures and low-dimensional structures [7,[12][13][14][15]. Materials with nanostructure and different morphologies are expected to improve the thermoelectric figure of merit ZT due to the quantum-confinement effects and the differences in their respective scattering lengths of internal interfaces [16].…”