Resonant tunnelling diode in MBE-grown delta-doped GaAs

A homotype negative differential resistance (NDR) device with GaAs delta-doped structure prepared by molecular beam epitaxy is demonstrated. Two Si and one Be delta-doped planes were inserted into the GaAs layer, i.e. n- delta n⁺-i- delta p⁺-i delta n⁺-n, to form the required resonant tunnelling structures. Electrons are thus transported from the conduction band of the n⁺ layer and resonantly tunnel through the light hole level of the delta p⁺ induced quantum well. Symmetrical NDR characteristics with high peak to valley current ratios (PVR) of 3 operated at room temperature can be achieved comparable with those of the heterotype AlGaAs/GaAs double barrier structure. The PVR decreases with decreasing temperature are due to the inherent properties of the widening effect of the energy gap at low temperature. The calculated transmission coefficient using the two-band model with the transfer matrix method confirmed the observations.