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.

Articles you may be interested inFrequency multiplication of microwave radiation by propagating space-charge domains in a semiconductor superlattice Appl.

We report 77.3 K self-oscillations in a 30-period weakly coupled GaAs/Al0.3Ga0.7As (28/10 nm) superlattice (SL). A study of frequency spectra of self-oscillations under external sinusoidal force in frequency-locked regime at different fixed voltages showed that current oscillations detected in the structureless regions of the I-V characteristic of weakly coupled SLs are forced oscillations. It was established that oscillations of free oscillator arising when the voltage is fixed at the first negative differential conductivity region at the beginning of the plateaulike region in the I-V characteristic are forcing oscillations. It was also shown that in order to describe the mechanism of the current oscillations in weakly coupled SLs, the model of the current oscillations in resonant tunneling diodes can be successfully applied.

The study of the bolometer response to terahertz (THz) radiation from a double-barrier resonant tunneling diode (RTD) biased into the negative differential conductivity region of the I–V characteristic revealed that the RTD emits two pulses in a period of intrinsic self-oscillations of current. The bolometer pulse repetition rate is a multiple of the fundamental frequency of the intrinsic self-oscillations of current. The bolometer pulses are detected at two critical points with a distance between them being half or one-third of a period of the current self-oscillations. An analysis of the current self-oscillations and the bolometer response has shown that the THz photon emission is excited when the tunneling electrons are trapped in (the first pulse) and then released from (the second pulse) miniband states.

No abstract