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Photon Detectors
Published in Antoni Rogalski, Zbigniew Bielecki, Detection of Optical Signals, 2022
Antoni Rogalski, Zbigniew Bielecki
The PbSe and PbS films used in commercial IR detectors are made by chemical bath deposition (CBD), the oldest and most-studied PbSe and PbS thin-film deposition method. The basis of CBD is a precipitation reaction between a slowly produced anion (S2– or Se2–) and a complexed metal cation. The commonly used precursors are lead salts, Pb(CH3COO)2 or Pb(NO3)2, thiourea [(NH2)2CS] for PbS and selenourea [(NH2)2CSe] for PbSe, all in alkaline solutions. Lead may be complexed with citrate, ammonia, triethanolnamine, or with selenosulfate itself. Most often, however, the deposition is carried out in a highly alkaline solution where OH– acts as the complexing agent for Pb2+.
2 thin films - electrical and optical properties
Published in R D Tomlinson, A E Hill, R D Pilkington, Ternary and Multinary Compounds, 2020
K.T. Ramakrishna Reddy, R.B.V. Chalapathy
In the present studies, CuGaxIn1–xSe2 thin films were prepared by the spray pyrolysis technique. The spray head (1/4 JAU Sys. Co. USA) was connected to a stepper motor system which was used to produce a uniform coating of the film on the substrate when the solution was sprayed. CuCl2, GaCl3, InCl3 and N, N-dimethyl selenourea were the compounds used for preparing the starting solutions and deionised water was used as the solvent. The concentrations of CuCl2 and GaCl3/InCl3 were maintained at 0.0015 M while that of selenourea was 0.0055 M. The concentrations of GaCl3 and InCl3 solutions were mixed appropriately to vary the gallium content in the films. The Cu:(Ga+In):Se atomic ratio in the starting solution was kept at 1:1:35. An excess of selenium over the stoichiometric amount was taken in order to compensate the loss of selenium during the deposition. Soda-lime glass was used as the substrate to deposit the films. The temperature of the substrates during the deposition was maintianed in the range of 300 – 350°C. The source to substrate distance was kept at 25 cm. Purified compressed air was used as the carrier gas at a flow rate of 6 1. min−1 while the solution flow rate was kept at 4 ml min−1. The thickness of the deposited films was about 600 nm. The deposition was carried out in a dark chamber to prevent the dissociation of N, N-dimethyl selenourea into elemental selenium.
IV–VI detectors
Published in Antoni Rogalski, Infrared and Terahertz Detectors, 2019
The PbSe and PbS films used in commercial IR detectors are made by chemical bath deposition (CBD); the oldest and most-studied PbSe and PbS thin-film deposition method. It was used to deposit PbS in 1910 [108]. The basis of CBD is a precipitation reaction between a slowly produced anion (S2− or Se2−) and a complexed metal cation. The commonly used precursors are Pb salts, Pb(CH3COO)2 or Pb(NO3)2, thiourea [(NH2)2CS] for PbS, and selenourea [(NH2)2CSe] for PbSe, all in alkaline solutions. Pb may be complexed with citrate, ammonia, triethanolnamine, or with selenosulfate itself. Most often, however, the deposition is carried out in a highly alkaline solution where OH− acts as the complexing agent for Pb2+.
An insight on the different synthetic routes for the facile synthesis of O/S-donor carbamide/thiocarbamide analogs and their miscellaneous pharmacodynamic applications
Published in Journal of Sulfur Chemistry, 2023
Faiza Asghar, Bushra Shakoor, Babar Murtaza, Ian S. Butler
Many selenocarbonyl compounds have been synthesized. Selenoureas are utilized as precursors in the synthesis of selenium-nitrogen heterocyclic compounds, and their activities are gaining popularity. Only a few studies exist on the synthesis of N,N-unsubstituted selenourea from hydrogen selenide and cyanamide. It is rare to see N,N-unsubstituted selenourea made without the use of toxic hydrogen selenide. The synthesis of N,N-unsubstituted selenourea using LiAlHSeH had also been studied. Koketsu et al. [53] presented a simple method for making N,N-unsubstituted selenoureas and thioureas by reacting cyanamides with a selenium- and sulfur-containing reagent [53].