Ultrafast Optical Nonlinearities in CdS Nanocrystalline Thin Films Prepared by Chemical Bath Deposition

Abstract

The dynamics of absorption bleaching in CdS nanocrystalline thin films were studied in the temperature interval 10-300 K and three distinct decay time constants (sub-ps, ps, and ns) were identified. We interpreted the dynamics in terms of three groups of nanocrystals with specific defects and showed that two of them are related. A close link between the temperature behaviour of the photoluminescence efficiency and that of the relative amplitude of the nanosecond component was observed and an explanation based on a microscopical model was proposed. The optical nonlinearities were studied by self-diffraction technique. A dephasing time constant shorter than 80 fs and a value of jc 3 j % 6 Â 10 --16 m 2 V --2 were obtained.

Anomalous disorder-related phenomena in InGaN/GaN multiple quantum well heterosystems

“…This interest has stimulated experimental investigations on the disordered properties. Recently, the Berthelot-type microscopic model has successfully described the characteristics of anomalous temperature-dependent behaviors in many disordered systems, such as polycrystalline InP thin films, porous Si semiconductors, CdS nanocrystalline thin films, and GaN-based heterostructures [2][3][4][5][6][7]. Studies on carrier transport in disordered systems indicate that the disordering predominantly follows a surface mechanism.…”

Anomalous temperature-dependent behaviors of electroluminescence phenomena in disordered ITO/PEDOT/PF/Ca/Al polymer light-emitting diodes

“…However, from a statistical order-disorder view, thermodynamical multiple-component phase separations in nitride-based alloys are considered to be similar to semiconductor amorphousness [3]. Recently, the Berthelot-type microscopic model has been used to successfully describe the linear and nonlinear temperaturedependent behaviors of many disordered systems, such as porous Sr 2 CrReO 6 ferrimagnets, porous Si semiconductors, and CdS nanocrystalline thin films [4][5][6][7]. Furthermore, light emission in OLEDs is obtained through a recombination of injected electrons and holes, which is unlike that in classical semiconductors.…”

Characterization of Berthelot-type behaviors of InGaN/GaN semiconductor heterosystems

“…However, in a statistical order-disorder view, thermodynamical multicomponent phase separations in nitride-based alloys are considered to be similar to semiconductor amorphousness [6]. Recently, the Berthelottype microscopic model has successfully described the linear and the nonlinear temperature-dependent behaviors of many disordered systems, such as porous Sr 2 CrReO 6 ferrimagnets, porous Si semiconductors, and CdS nanocrystalline thin films [7][8][9][10]. In this work, concerning the thermal-related attributes arising from InGaN microstructure disordering, the characteristics of the InGaN/GaN MQW p-i-n heterostructures composed of InGaN/GaN multiple quantum barriers (MQBs) have been studied as a function of the InN molar fraction.…”