Visualization of current filaments in n-GaAs by photoluminescence quenching

Abstract

Hot electrons in semiconductors are known to quench radiative impurity and exciton recombination photoluminescence. This effect has been applied in a low invasive technique to determine the spatial form of current filaments generated by impurity breakdown in high purity n-GaAs epitaxial layers at low temperatures. Observations on samples with Corbino disc contacts clearly demonstrate symmetry breaking and self-organization by the current filamentation.

Discontinuities and Hysteresis in the I–V Characteristics of n-GaAs at Low Temperatures

“…The operating point switches to the stable configuration of the decreasing branch upon illumination with visible light. Hence a continuous reconstruction of a filament on the increasing branch by the laser scanner or by other means like quenched luminescence [18] was impossible. Therefore a dynamic technique of reconstruction has been used operating the laser in a pulsed mode.…”

“…Compared to the scanning electron microscope, laser scanning has the advantage that the effect of an external magnetic field on current filaments can easily be studied. More recently a very elegant method has been developed to make visible impurity breakdown-induced filaments [14] and electron density structures [15]. The method is based on quenched luminescence by hot electrons.…”

Anomalous PL brightening caused by impact formation of a (D + , X) complex during an impact ionization avalanche in n‐GaAs

“…During the impact ionization avalanche, the impact ionization process of the excitons bound to the ionized donors competes with the impact formation processes (2) and (3). Figure 3 shows the PL spectra as a function of the pulse voltage V 0 , where the photoexcitation density was much higher than J p ≈ 63 µW/cm 818.7 nm decreases more rapidly than the (D + , X) emission line at 819.3 nm.…”

“…The current density filament can be seen as a bright PL pattern between the two ohmic contacts (short circuitry conditions). The width of the filament increases by increasing the applied pulse voltage [3,5,9]. In the present experiments, the amplitude of the applied pulse voltage was settled to be larger than the breakdown voltage.…”

“…By the low-temperature impurity breakdown, a current density filament can be formed between the ohmic contacts [1, 2]. The current density filament has been typically observed as a photoluminescence (PL) quench-pattern [3].By the PL method, Aoki and Fukui [4−6] have investigated the nucleation process of a current density filament [4] and also the nonlinear dynamics of the filament during the current instability under magnetic fields in n-GaAs [1,5,6]. Very recently, the author has found, that the PL pattern image under a short pulse voltage can be seen as a bright pattern inside the filament or along the filament boundaries in a n-GaAs Corbino disc [7,8], where the anomalous brightening of the PL intensity was seen under a very weak photoexcitation density.…”