We demonstrate that the modulated surface photovoltage spectroscopy (modulated SPS) technique can be applied to investigate interface states in the bandgap, i.e. interface passivation, of crystalline silicon coated with a downshift layer such as hydrogenated aluminum nitride with embedded terbium ions by suppressing straylight with a cut-off filter. Different hydrogen contents influence the surface photovoltage spectra at photon energies below the bandgap of crystalline silicon. Modulated SPS reveals that at higher hydrogen content there is a lower signal and, thus, a lower density of surface defect states. Our experiments show that modulated SPS can become a powerful tool for characterizing defect states at interfaces which cannot be easily studied by other methods. © 2021 Published under licence by IOP Publishing Ltd.

Se presenta el caso de una paciente mujer, adulta mayor, sin antecedentes de consumo de alcohol ni medicamentos o sustancias hepatotóxicas, con estudios serológicos para hepatitis viral negativos, en la que se evidencia daño hepático crónico ( Score B en la escala de Child-Turcotte-Pugh), la cual presenta características clínicas, serológicas, inmunológicas e histológicas mixtas entre Hepatitis Autoinmune y Cirrosis Biliar Primaria, postulándose un síndrome de “sobreposición” u overlap.

Surface passivation is a widely used technique to reduce the recombination losses at the semiconductor surface. The passivating layer performance can be mainly characterized by two parameters: The fixed charge density (Q(ox)) and the interface trap density (D-it) which can be extracted from Capacitance-Voltage measurements (CV). In this paper, simulations of High-Frequency Capacitance-Voltage (HF-CV) curves were developed using simulated passivation parameters in order to examine the reliability of measured results. The D-it was modelled by two different sets of functions: First, the sum of Gaussian functions representing different dangling bond types and exponential tails for strained bonds. Second, a simpler U-shape model represented by the sum of exponential tails and a constant value function was employed. These simulations were validated using experimental measurements of a referenc...

The authors would like to acknowledge the financial support of the Peruvian science foundation Cienciactiva in the framework of the DAAD-CONCYTEC joint project (2017-2019), the “Círculo de investigación” project and the Research Management Office (DGI) of the Pontificia Universidad Católica del Perú (PUCP). The research activity was performed in the framework of the doctoral scholarship of K. Tucto and L. Flores from CONCYTEC under the contract numbers 012-2013-FONDECYT and 000236-2015-FONDECYT-DE, respectively. The authors are also grateful to the Center of Microcharacterization (CAM) of the PUCP for the EDX and PL measurements.