Conduction mechanism analysis in β-FeSi2/n-Si heterojunction throughJ–V–Tmeasurement

Abstract

The p-type iron disilicide (-FeSi 2 ) semiconductor was formed at room temperature without heat treatment due to the superiority of the employed unbalanced magnetron sputtering technique on n-type crystalline silicon (n-Si), and conduction mechanism(s) of the resulting p--FeSi 2 /n-Si heterostructure was investigated by current density-voltage-temperature (J-V-T) measurement in darkness condition under vacuum after evaporation of both chromium (Cr) and gold (Au) metals as the front electrode.Two different current mechanisms seemed to be dominant on Cr/-FeSi 2 /n-Si and Au/-FeSi 2 /n-Si heterostructures, respectively.The transition of one mechanism to another occurred in a particular bias voltage range: between 3 kT/q and 0.3 V, the multistep tunneling capture emission (MSTCE) mechanism became dominant with an activation energy (E A ) around 0.3 eV for both forward and reverse directions of bias and interpreted as an Fe impurity.Also, the reverse current density had a square-root dependence on reverse bias voltage, thus proposing generation current.In this frame, at an E A of 0.3 eV above the valance band edge denoted the efficient trap level for the recombination-generation mechanism in the -FeSi 2 semiconductor or at the interface of the -FeSi 2 /Si heterojunction.Subsequently, as the second mechanism, space charge limited current (SCLC) started at a high forward bias voltage region (from 0.65 V to 1 V), where the power of the bias (m) changed from high to low value as the ambient temperature was increased (110 K to 380 K).A further increase in bias voltage (above 1 V) yielded a series resistance region where thermally activated current was observed, representing a conduction band offset, E c .Its value was determined as 0.16 eV, consistent with the announced values in the literature.