Optical study of a tunable-density two-dimensional electron gas in a CdTe/CdZnMgTe single quantum well

Modulation-doped single quantum wells inserted in a Schottky diode have been fabricated to allow varying the electron density of a two-dimensional electron gas (n(c)) in the CdTe quantum well by applying a reverse bias voltage. The optical transition that creates the negatively charged exciton (X-) is studied as a function of II, under a magnetic field. At 8 T, the X-absorption grows linearly with n(e) for Landau level filling factor v < 1, reaches a maximum when v = 1 and decreases linearly when v > 1 back to zero when v = 2. (C) 1998 Elsevier Science B.V. All rights reserved.