The 2-D-3-D crossover in modulation-doped GaAs-Ga/sub 1-x/Al/sub x/As quantum wells

We report on a method to analyze the 2-D-3-D crossover in n-type modulation-doped quantum wells. Finite well barrier, first and second subband population, many-body effects, and residual doping are included in our calculation. We found that the 2-D-3-D crossover remarkably depends not only upon the geometrical parameters, as for instance, the spacer layer width and quantum-well width, but also upon a residual p-type doping intentionally introduced. A diagram showing the 2-D-3-D dimensional crossover is presented.