ELECTRONIC-PROPERTIES OF ALXGA1-XSB INAS QUANTUM-WELLS/

We have studied the electronic properties of Al(x)Ga1-xSb/InAs quantum wells, including the negative persistent photoconductivity effect, th e magnetic-field-induced semimetal-to-semiconductor transition, and th e sources of electron accumulation. We have also demonstrated that the negative persistent photoconductivity effect observed in these quantu m wells can be used as a tool to investigate not only the electron-den sity dependence of the semimetal-to-semiconductor transition but also the alloy dependence of ionized deep donors in the Al(x)Ga1-xSb barrie r layers. We found that negative persistent photoconductivity is a gen eral property in this quantum-well system and the saturated reduction of the electron density due to the negative persistent photoconductivi ty effect increases with Al composition. From the alloy dependence of the electron density, we believe that the electrons removed from the I nAs well after the illumination are captured by the ionized deep donor s in the Al(x)Ga1-xSb layer, and that the deep donor level is not the only source of electron accumulation in the InAs well.