Magnetotransport and luminescence measurements in an n-type selectively doped InGaAs/GaAs strained quantum well structure

A selectively doped, n-type, single strained quantum well (SSQW) structure, consisting of an 8-nm-thick In/sub 0.25/Ga/sub 0.75/As layer sandwiched between thick GaAs layers, has been grown by molecular beam epitaxy. Low-field Hall-effect measurements from 4 to 300 K and field-dependent magnetotransport measurements at 4 K show that conduction through the doped GaAs layers competes with conduction from the two-dimensional electron gas confined by the InGaAs quantum well. Photoluminescence measurements at 4 K yield a band-gap energy of 1.30 eV and confirm the transport measurement of carrier density in the InGaAs conducting channel. Analysis of the parallel-conduction process yields channel carrier density and mobility which are consistent with data on strained-layer superlattices (SLS's) not exhibiting parallel conduction. Comparison of the SSQW and SLS results demonstrates that heavily doped SSQW structures require narrow doping spikes to avoid parasitic current paths