Effect of Si δ doping and growth temperature on the I(V) characteristics of molecular-beam epitaxially grown GaAs/(AlGa)As resonant tunneling devices

Abstract
(AlGa)As–GaAs–(AlGa)As double barrier resonant tunneling diodes with different δ‐doping levels in the GaAs quantum well (QW) together with undoped control samples have been investigated. A new subthreshold peak in the I(V) characteristics is observed and assigned to resonant tunneling through the bound state of a shallow donor impurity in the QW. By comparing the I(V) characteristics for wafers grown at different temperatures between 480 and 630 °C, the effects of Si segregation from contact layers into the well can be identified. This constitutes a new technique of assessment of donors which is sensitive to areal doping densities as low as 107 cm−2. The effect of low growth temperature (480 °C) and δ doping on peak/valley ratios of the resonances on the I(V) characteristic is also assessed.