Current-voltage characteristics of high current density silicon Esaki diodes grown by molecular beam epitaxy and the influence of thermal annealing

We present the characteristics of uniformly doped silicon Esaki tunnel diodes grown by low temperature molecular beam epitaxy (T-growth = 275 degrees C) using ill situ boron and phosphorus doping. The effects of ex situ thermal annealing are presented fur temperatures between 640 and 800 degrees C. A maximum peak to valley current ratio (PVCR) of 1.47 was obtained at the optimum annealing temperature of 680 degrees C for 1 min. Peak and valley (excess) currents decreased more than two orders of magnitude as annealing temperatures and times were increased with rates empirically determined to have thermal activation energies of 2.2 and 2.4 eV respectively. The decrease in current density is attributed to widening of the tunneling barrier due to the diffusion of phosphorus and boron, A peak current density of 47 kA/cm(2) (PVCR 1.3) was achieved and is the highest reported current density for a Si-based Esaki diode (grown by either epitaxy or by alleging). The temperature dependence of the curl-ent voltage characteristics of a Si Esaki diode in the range from 4.2 to 325 K indicated that both the peak current and the excess current are dominated by quantum mechanical tunneling rather than by recombination. The temperature dependence of the peak and valley currents is due to the hand gap dependence of the tunneling probability.