Current bistability and switching in weakly coupled superlattices GaAs/AlGaAs

Abstract

Current–voltage characteristics of 30 period 390 Å GaAs/110 Å Al0,3Ga0,7As superlattices are studied. Features revealed in multistable current branches of the hysteresis loops made it possible to estimate gradual changes in the size and shape of the domain boundary and reconstruct the final shape of the domain boundary. It was concluded that a considerable current bistability observed in the investigated superlattices is due to the domain boundary expansion. Switching between bistable current states in each hysteresis loop is detected. The switching time depends on the direction of the current jump. The switching time from a high- to low-current state is about 10−7 s; the time of the reverse switching to the high-current state is about 10−6 s. The observed switching is attributed to the shrinkage and expansion of the domain boundary size.

Capacitance–voltage characteristics of weakly coupled superlatticesGaAs/AlGaAs

“…As we supposed earlier [15] the current branches measured in the I -V characteristics carry information about the spatial redistribution of the space charge layer forming the domain wall. Since each capacitance or conductance peak is related to a definite SL period, important information about changes in the spatial distribution of the space charge layer can be extracted from the C-V characteristics.…”

“…From the study of I -V characteristics on SL structures with large current bistability (hysteresis) [15], following the model of intrinsic bistability in Double Barrier Resonant Tunneling Structures (DBRTS) [16,17], we have assumed that the observed current hysteresis is a result of the domain boundary expansion produced by electrons stored in quantum wells (QWs). Based on this study, we have proposed a simple method for estimation of the value of the domain boundary expansion [15].…”

“…Based on this study, we have proposed a simple method for estimation of the value of the domain boundary expansion [15]. To prove the validity of the suggested method, a study of C-V characteristics that can provide straightforward information of the space charge layer forming the domain boundary was initiated.…”

“…In our recent publication [15], we have supposed that the expanded domain boundary manifests itself as a relative voltage shift of NDC peaks of the same number of high-and low-conductance curves of hysteresis [16,17] has been used. Following this model, we assumed that electrons are dynamically stored in QWs, and the resulting space charge modifies the potential profile of the barriers that affects the relative coupling energy of resonant levels in neighbouring QWs.…”

“…Since each capacitance or conductance peak is related to a definite SL period, important information about changes in the spatial distribution of the space charge layer can be extracted from the C-V characteristics. The C-V transition lines joining the up-and down-sweep capacitance peaks were measured by the same method as we have used for the current branches measurements [15]. In Figs 3 and 4 the C-V and I -V characteristics for the third hysteresis loop are presented.…”