Electronic properties of £_-doped InxGa1-xAs/InAlAs Quantum wells

by Chen, Jyun-fan

We have studied the electronic properties of InxGa1-xAs/ In0.52Al0.48As quantum wells by using Shubnickove-de Hass (SdH) measurement. The indium composition (x) of well layers was varied from 0.5 to 0.56 whit different structures, such as sample A is simply ¡§In0.53Ga0.47As¡¨, sample B is a step-well like¡§In0.56Ga0.44As/In0.53Ga0.47As/In0.5Ga0.47As¡¨,sample C is linearly graded well is a opposite way¡§In0.56Ga0.44As down to In0.5Ga0.5As, and sample D is linearly graded well ¡§In0.5Ga0.5As up to In0.56Ga0.44As.¡¨ It was found that the two SdH oscillations beat each other due to the population of the lowest two subbands in these samples. In order to investigate the electronic properties of the two subbands, we have done the Ven der Pauw Hall measurement . From SdH and Hall measurement, we are able to determine the individual mobility and carrier concentrations for two-subband-populated samples.