Abstract
The effect of methane/hydrogen (CH4/H2) reactive ion etching (RIE) and a subsequent annealing process on AlGaAs/GaAs and pseudomorphic AlGaAs/InGaAs/GaAs heterostructures has been investigated, using low temperature Hall, Shubnikov–de Haas, and photoluminescence measurements. It is observed that the electron density and mobility of the two-dimensional electron gas in the heterostructure are strongly reduced by the RIE process. After annealing, the electron density and the electron mobility recover fully for the pseudomorphic AlGaAs/InGaAs/GaAs heterostructures. This is confirmed by photoluminescence measurements at low temperatures. For the AlGaAs/GaAs heterostructures the electron density recovers fully, but the electron mobility recovers to only 60% of the reference value at 4·2 K. This indicates that in the AlGaAs/GaAs heterostructures the structural damage induced by RIE is not fully removed by thermal annealing. Shielding of the influence of the plasma treatment by incorporating a silicon δ-doped layer in the AlGaAs/GaAs heterostructures results in a pronounced enhancement of the recovery of the electron mobility of the two-dimensional electron gas at 4·2 K from 60 to 75%.
MST/3223
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