Observation of charged X−and X+excitons and metal-to-insulator transition in CdTe/CdMgZnTe modulation-doped quantum wells

✍ Scribed by A. Haury; A. Arnoult; V.A. Chitta; J. Cibert; Y. Merle d'Aubigné; S. Tatarenko; A. Wasiela

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 107 KB
• Volume: 23
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1006/spmi.1996.0232

✦ Synopsis

The positively and negatively charged excitons, X + and X -, respectively, are identified by their magnetic circular dichroism in the absorption spectra of modulationdoped CdTe/Cd 0.69 Mg 0.23 Zn 0.08 Te multiple quantum wells at small carrier densities (≈ 10 10 cm -2 ). In these quantum wells with a width of 8 nm the binding energies of the second electron of the X -exciton and of the second hole of the X + exciton are very similar, 2.9 meV and 2.6 meV, respectively. At larger hole densities a transition to the conducting state is observed. In a sample with intermediate hole density (low 10 11 cm -2 ) the insulating phase is restored by application of a magnetic field.