A new GaAs sawtooth-doping-superlatticed switching device

A GaAs switching device with a double sawtooth-doping-superlattice (SDS) structure has been fabricated and demonstrated. By using the Kronig-Penny model, the dispersion relations of the electrons and holes in the zigzag quantum well were investigated. Two different delta-doping sheets, 1 × 10¹² and 1 × 10¹³ cm^-2, were used in the double SDS structure. The period length of the SDS was 600 Å. Thus, due to the sufficient barrier height and width, the calculated transmission coefficient of electrons was negligible when the studied structure was at thermal equilibrium or under a small-biased condition. However, when a larger bias was applied, the studied structure exhibited an interesting negative-differential-resistance (NDR) performance in the experimental current-voltage characteristics. This was caused by an avalanche multiplication process and the potential redistribution in SDS periods. Particularly, an interesting intermediate state between the initial off state and final on state was observed at 77 K. Consequently, with a suitable adjustment of structural parameters, e.g., the delta-doping density and the period number of the SDS, the proposed device provides good potential for switching circuit applications.