Carrier transport mechanisms in reverse biased InSb p-n junctions

Abstract

Abstract. Carrier transport mechanisms have been investigated in linearly graded InSb p-n junctions prepared using thermal diffusion of Cd into single crystal substrates of ntype conductivity. The investigations were focused on the reverse current as a function of bias voltage and temperature. The obtained experimental data show that local inhomogeneities in the depletion region are responsible for the excess tunneling current observed in the reverse biased junctions. The inhomogeneities have been attributed to dislocations, precipitates or other extended defects. A phenomenological model is proposed to explain experimental data.

Electrical properties of InSb p-n junctions prepared by diffusion methods

“…The breakdown voltage U B that is measured at the current density 1.0 A/cm 2 [19] was 2.3, 5.4 and 7.5 V for TR1, TR2 and TR3 junctions, respectively. Experimental values of m and U B for TR1 and TR2 junctions can be explained within a model of tunneling breakdown in the inhomogeneous p-n junction [14]. A sharp increase in the current in TR3 junction and higher values of the breakdown voltage can be explained by the avalanche breakdown [9].…”

“…However, additional investigations are required for it. It should be pointed out that in TR3 junction the dark current density at the reverse bias 0.2 V equals to 3.2·10 -6 A/cm 2 , which is several orders of magnitude less than the values reported in literature [3,6,7,14]. However, this value exceeds almost three times the theoretical one required to implement BLIP regime in InSb photodiodes [4].…”

“…It can be explained by passivation of mezas with cadmium telluride as well as the higher quality of the junction itself. The detailed analysis of tunnel currents in diffusion InSb junctions is given in [12,14]. An additional evidence of the TR3 junction quality was obtained from the analysis of generation current at the reverse biases.…”

“…This model involves uniform distribution of deep traps through the depletion region [8,11]. On the contrary, in a model of non-homogeneous p-n junction, carrier tunnelling with participation of extended defects, such as dislocations, is assumed to be responsible for the excess current [12,14]. In this case, local areas exist in the depletion region, which are characterized by higher electric field.…”

“…High concentration of point and extended defects in freshly prepared junctions results in a problem of separation of electrical and metallurgical junctions. In implanted photodiodes, this problem is resolved by photonic or thermal annealing [4], whereas in diffusion ones two-temperature diffusion method is used [9,12,14].…”