Simultaneous Interface Defect Density and Differential Capacitance Imaging by Time-Resolved Scanning Nonlinear Dielectric Microscopy

We investigate non-uniformity at SiO2/SiC interfaces by time-resolved scanning nonlinear dielectric microscopy, which permits the simultaneous nanoscale imaging of interface defect density (Dit) and differential capacitance (dC/dV) at insulator-semiconductor interfaces. Here we perform the cross correlation analysis of the images with spatially non-uniform clustering distributions reported previously. We show that Dit images are not correlated with the simultaneous dC/dV images significantly but with the difference image between the two dC/dV images taken with different voltage sweep directions. The results indicate that the dC/dV images visualize the non-uniformity of the total interface charge density and the difference images reflect that of Dit at a particular energy range.

Modeling of an elastic field scattered by an interface defect

The problem of the shear-wave (SH-wave) diffraction from the semi-infinite interface defect in the rigid junction of the elastic layer and the half-space is solved. The defect is modeled by the impedance surface. The dependences of the scattered displacement field, reflection and transmission coefficients on the structure parameters are presented in analytical form. The examples of numerical modeling of field characteristics are provided.

Simulation of a Charged Al2O3 Film As An Assisting Passivation Layer For a-Si Passivated Contact p-Type Silicon Solar Cells

In this paper, a charged Al2O3 tunneling film as an assisting for amorphous Si (a-Si) passivated contact layer is proposed and theoretically simulated for its potential application in improving a-Si passivated contact p-type (a-PC-p) solar cell. The concept is based on an Ag/n+ c-Si/p c-Si/Al2O3/p+ a-Si/Al structure. The key feature is the introduction of a charged Al2O3 layer, which facilitates the tunneling of holes through an Al2O3 insulator layer accompanied by the reduction of interface defect density (Dit). The negative charge in the Al2O3 layer makes the energy band of p-type c-Si bend upward, realizing the accumulation of holes and repelling of electrons at the c-Si/a-Si interface simultaneously. The influence of interface negative charges (Qit) between a-Si and c-Si, Al2O3 thickness, Al2O3 bandgap, interface defect density (Dit) at the a-Si/c-Si interface are systematically investigated on the output parameters of a-PC-p cells. Inserting a charged Al2O3 film between the c-Si/a-Si interface, a +4.2 % relative efficiency gain is predicted theoretically compared with the a-PC-p cells without the Al2O3 layer. Subsequently, the device performance under various temperatures is simulated, and the insertion of a charged Al2O3 layer obviously decreases the Pmax temperature coefficient from -0.336 % /℃ to -0.247 % /℃, which is analogous to that of Heterojunction with Intrinsic Thin layer (HIT) solar cell. The above results demonstrate a better temperature response for a-PC-p cells with a charged Al2O3 layer, paving a road for its potential application in high-efficiency and high thermal stability a-PC-p solar cells.