MAGNETOOPTICAL PROPERTIES OF THE EXCITONS IN FRACTIONAL-MONOLAYER ZNTE STRUCTURES AND ZNTE ISLAND SELF-ORGANIZING EFFECTS

Structures consisting of ZnTe fractional-monolayers inserted coherentl y in a CdTe quantum well are investigated by absorption measurements a nd spin-quantum beat measurements. Many sharp exciton transitions are observed. The effective g-factor of the excitons and the electron g-fa ctors involved in those excitons are measured by Zeeman measurements a nd by spin-quantum beat measurements, respectively. The experimental r esults shaw that the strained ZnTe islands can strongly modify the exc itonic transitions related to the quantization of the excitonic center -of-mass motion (CM quantization). We will show that the striking incr ease in the effective g-factor of the Chl-quantized excitons is due to the change of the hole g-factor involved, since it is found experimen tally that the electron g-factor is unchanged. The experimental result s also show that a coherent distribution of the ZnTe islands is formed at higher growth temperature (greater than or equal to 280 degrees C) , while a random distribution of the ZnTe islands is present at lower growth temperatures (less than or equal to 240 degrees C). (C) 1998 El sevier Science B.V. All rights reserved.