Tunneling Spectroscopy of Resonant Transmission Coefficient in Double Barrier Structure

It is theoretically pointed out that the tunneling spectroscopy technique offers us a method to evaluate the resonant tunneling transmission coefficients of double barrier structure: the transmittance function is proportional to the second derivative of I-V characteristics. Peaked transmittance of the first resonance level was, indeed, measured in an AlAs(2.3 nm)-GaAs(5.4 nm)-AlAs(2.3 nm) double barrier structure. It was found that the measured half width at half maximum of the peak was 15 meV which is 220 times larger than a predicted value (∼69 µeV) calculated with a simple Kronig-Penny type model, while the peak height was reduced from unity by a factor of 950. The width is, however, in good agreement with width of photoluminescence peak from the structure. The results imply presence of energy broadening mechanisms in the resonant tunneling structure.