Anomaly of the current self-oscillation frequency in the sequential tunneling of a doped GaAs/AlAs superlattice

Abstract

An anomalous behavior of the current self-oscillation frequency is observed in the dynamic dc voltage bands, emerging from each sawtoothlike branch of the current-voltage characteristic of a doped GaAs/AlAs superlattice in the transition process from static to dynamic electric field domain formations. Varying the applied dc voltage at a fixed temperature, we find that the frequency increases while the averaged current decreases. Inside each voltage band, the frequency has a strong voltage dependence in the temperature range where the averaged current changes with the applied dc voltage. This dependence can be understood in terms of motion of the system along a limit cycle.

Discrete self-oscillation period branches observed in semiconductor superlattices

“…39 However, few papers focus on the voltage dependence of the oscillation period in the DVB region, except the works in Refs. 35,38,40, where the oscillation frequency was found to increase first and then decrease with increasing voltage. In the present work, we investigate the voltage dependence of the current oscillation period in the DVB region in a microscopic resonant tunneling model.…”

“…2 agrees well with the results reported in previous works. 35,38 Here, we observe two new phenomena: (1) A new period branch (branch number 0) appears at the left side of the DVB region. (2) It is shown that the U-shaped period curve is divided into many discrete branches.…”

“…With increasing temperature, the DVBs will emerge at the low voltage side of the SVBs, then expand, and finally squeeze out the SVBs. 34,35 If ac bias condition is applied, the I-V characteristic curve in the DVB region becomes discrete, which is related to a period-adding bifurcation. 39 However, few papers focus on the voltage dependence of the oscillation period in the DVB region, except the works in Refs.…”

“…34 In previous works, [34][35][36][37][38][39][40] the influences of the system temperature and external ac bias on I-V characteristics in the DVB region have been fully investigated. With increasing temperature, the DVBs will emerge at the low voltage side of the SVBs, then expand, and finally squeeze out the SVBs.…”

Noise-Induced Oscillations and Their Control in Semiconductor Superlattices

“…For instance, negative differential conductance can appear [Esaki & Tsu, 1970] (see Fig.1(b)). Thus, semiconductor superlattices can be used as generators of current oscillations, whose frequency depends on the parameters of the superlattice structure and the applied voltage, and thus, can be varied in a wide range from some hundred kHz [Cadiou et al, 1994;Hofbeck et al, 1996;Kastrup et al, 1995;Wang et al, 2000] to hundreds of GHz [Schomburg et al, 1999], which makes this system very promising for practical applications. On the other hand, the inherent nonlinearity gives rise to complex spatio-temporal dynamics of the charge density and the field distribution within the device, including the formation of travelling charge accumulation and depletion fronts and field domains associated with current oscillations.…”