The Photo-Conductivity of "Incomplete Phosphors"

Abstract

Synthetic single crystals of CdS, CdSe, and CdTe have been produced by the reaction of cadmium vapor with H2S, H^Se, and HgTe, respectively, These "incomplete phosphors" show no phosphorescence but strongly developed photo-conductivity. Photo-cells made from these crystals are extremely sensitive in the whole region from the infra-red down to the ultraviolet, x-rays, and gamma-rays and for corpuscular rays, alpha-and beta-rays. Two different mechanisms of photo-conductivity occur. The normal photo-conductivity in the region of strong absorption from the blue to the ultraviolet, and the selective photo-conductivity in the region of weak absorption in the visible, x-rays, and corpuscular-rays region. The phenomena observed are in general accordance with the zonal theory of phosphorescence.

Effect of Fluxoid Quantization on Transitions of Superconducting Films

“…For bulk superconductors in geometries which eliminate demagnetizing effects (i.e., field parallel to long dimension), this leads to the thermodynamic critical field H C b given by F n (r)-F a (r) = F c& V8ir, (1) where F n and F s are the free energies of normal and superconducting state, respectively. It is also well known that when one considers a film of thickness comparable to the penetration depth, the critical field HT at which the transition to the normal state occurs is increased above H c b> provided the field is applied parallel to the surface.…”

“…1 order. In such a second-order transition, as H is increased toward HT, the order parameter (energy gap, "number of superconducting electrons," or Ginzburg-Landau ^ function) approaches zero continuously, while the penetration depth X increases from \ e (T) to infinity.…”

Vapour growth of bulk crystals by PVT and CVT

“…Scheme (1.2) is exemplified by the decomposition of SiH 4 (g) in a flow of H 2 (g) to deposit Si(s) [25], while the Frerichs method [26] for growing CdS and ZnS crystals through the reaction…”

Controlled Preparation and X-Ray Investigation of Cadmium Sulfide

“…The vapor phase method has the advantage that most impurities are separated by fractionate sublimation (2) so that purification of the Cd metal is not necessary. The light sensitivity of such crystals, however, was found (5-7) to be very different, even for crystals of the same batch.…”