Band-Offset Determination for Intrinsic a-Si/ p+μc-Si or Intrinsic a-Si/n+νc-Si Heterostructure

Abstract

ABSTRACTThe conduction band ΔEcand valance band ΔEv, off-sets at interfaces are critical parameters for device simulation. With the transport simulation code AMPS we demonstrate the possibility of using an analysis of the far forward I-V characteristics versus temperature for i- layer /n+or i-layer /p+hetero structures to obtain ΔEcor AE., respectively. For example, if one wants to extract AE, from experimental data for the interface a-Si/uc n+Si interface, we show this can be done using a metal/intrinsic a-Si:H/uc n+Si structure. With proper choice of the metal, the hole barrier height at the metal can be made large enough that the far forward current is only carried by electrons. We have found that, with the proper choice of structure thickness this far forward current can be controlled by ΔEcand not by space charge limited current. Unlike the work of Arnold et al [1], we have found that the choice of structure thickness is critical. In this case of an a-Si/uc n+structure this far forward current is actually controlled by ΔEC+ΔVnwhere ΔVnis the activation energy in the n+uc-Si layer. Since ΔVncan typically be ∼ 0.05eV in uc-Si, we see that ΔEcis essentially controlling this far forward current. To demonstrate the approach for the case of an a-Si/uc n+Si interface we consider different i-layer thicknesses.