15 research outputs found
Low frequency noises and DLTS studies in HgCdTe MWIR photodiodes
International audienceBoth low frequency noises and electrically active defects have been investigated for two technological variants, i.e. optimized and non-optimized, of the HgCdTe p on n technology applied to the mid wave infrared (MWIR) blue band with a cutoff wavelength of 4.2 ”m. This has been achieved using electro-optical characterizations and the deep level transient spectroscopy (DLTS) technique. The results show that the impact of extra 1/f and random telegraph signal (RTS) noises has been reduced with the optimization of the technology. Furthermore, a broadened DLTS peak, probably related to dislocations in the material, has been found for both variants, the relative amplitude of which is reduced in the optimized case. The potential correlation between low frequency noises and this broadened peak is discussed
Synthetic, structural, and spectroscopic studies of sterically crowded tin-chalcogen acenaphthenes
The work in this project was supported by the Engineering and Physical Sciences Research Council (EPSRC) and EaStCHEM.A series of sterically encumbered peri-substituted acenaphthenes have been prepared containing chalcogen and tin moieties at the close 5,6-positions (Acenap[SnPh3][ER], Acenap = acenaphthene-5,6-diyl, ER = SPh (1), SePh (2), TePh (3), SEt (4); Acenap[SnPh2Cl][EPh], E = S (5), Se (6); Acenap[SnBu2Cl][ER], ER = SPh(7), SePh (8), SEt (9)). Two geminally bis(peri-substituted) derivatives ({Acenap[SPh2]}2SnX2, X = Cl (10), Ph (11)) have also been prepared, along with the bromoâsulfur derivative Acenap(Br)(SEt) (15). All 11 chalcogenâtin compounds align a SnâCPh/SnâCl bond along the mean acenaphthene plane and position a chalcogen lone pair in close proximity to the electropositive tin center, promoting the formation of a weakly attractive intramolecular donorâacceptor E···SnâCPh/E···SnâCl 3c-4e type interaction. The extent of EâSn bonding was investigated by X-ray crystallography and solution-state NMR and was found to be more prevalent in triorganotin chlorides 5â9 in comparison with triphenyltin derivatives 1â4. The increased Lewis acidity of the tin center resulting from coordination of a highly electronegative chlorine atom was found to greatly enhance the lp(E)âÏ*(SnâY) donorâacceptor 3c-4e type interaction, with substantially shorter EâSn peri distances observed in the solid state for triorganotin chlorides 5â9 (âŒ75% ârvdW) and significant 1J(119Sn,77Se) spinâspin coupling constants (SSCCs) observed for 6 (163 Hz) and 8 (143 Hz) in comparison to that for the triphenyltin derivative 2 (68 Hz). Similar observations were observed for geminally bis(peri-substituted) derivatives 10 and 11.PostprintPeer reviewe