Differential Absorption Spectroscopy of Double-Barrier Tunnel Structures

We report the first application of differential absorption spectroscopy to the study of double-barrier resonant-tunneling structures. Two samples, grown by molecular beam epitaxy on InP substrates, have been studied. 

Structures consisted of a 45angstroms In sub (0.53) Ga sub (0.47) As quantum well, separated from 5x10 sup 17 cm sup -3 n-doped In sub (0.53) Ga sub (0.47) As electrodes by In sub (0.52) Al sub (0.48) As barriers of either 56 or 70angstroms in thickness. The formation of accumulation and depletion regions on either side of the double barrier is observed, as well as the buildup of charge in the quantum well of the device.