Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

This work reports a process based on the use of an ultrathin (10 nm) ZnO intermediate layer for the improvement of the absorber/back contact interface region in Cu₂ZnSnSe₄ (CZTSe) kesterite solar cells. Raman microprobe measurements performed directly on the substrate surface after mechanical removal of the absorber layer indicate the occurrence of a decomposition reaction of Cu₂ZnSnSe₄ in contact with the Mo substrate. This leads to a significant degradation of the quality of the absorber/back contact interface, with the formation of a high density of voids. The presence of an intermediate ZnO layer on the Mo coated substrates inhibits the decomposition reaction, because it prevents interaction between the CZTSe and Mo layers during the annealing process. This leads to a significant improvement in the interface morphology as observed by detailed cross-section scanning electron microscopy. It also correlates with the observed increase of the device conversion efficiency from 2.5% up to 6.0%. The improvement in the optoelectronic characteristics of the cells could be related to a significant decrease of the device series resistance due to the formation of a smoother interface with low density of voids, resulting from the effective inhibition of the CZTSe decomposition reaction at the Mo back contact layer.

In order to deepen the knowledge of the vibrational properties of two-dimensional (2D) MoS ₂ atomic layers, a complete and systematic Raman scattering analysis has been performed using both bulk single-crystal MoS ₂ samples and atomically thin MoS ₂ layers. Raman spectra have been measured under non-resonant and resonant conditions using seven different excitation wavelengths from near-infrared (NIR) to ultraviolet (UV). These measurements have allowed us to observe and identify 41 peaks, among which 22 have not been previously experimentally observed for this compound, and characterize the existence of different resonant excitation conditions for the different excitation wavelengths. This has also included the first analysis of resonant Raman spectra that are achieved using UV excitation conditions. In addition, the analysis of atomically thin MoS ₂ layers has corroborated the higher potential of UV resonant Raman scattering measurements for the non-destructive assessment of 2D MoS ₂ samples. Analysis of the relative integral intensity of the additional first- and second-order peaks measured under UV resonant excitation conditions is proposed for the non-destructive characterization of the thickness of the layers, complementing previous studies based on the changes of the peak frequencies.

We demonstrate for the first time, the real lifetime response of mixed halide perovskite solar cells (PSCs) for >1000 h under outdoor conditions and the exceptional photoresponse observed at low-light intensities attributed to the ionic-electronic nature of the material. The investigated devices were fabricated by utilizing mixed perovskites containing formamidinium (FA) and methylammonium (MA) cations, in a one step solution-process method through a solvent engineering approach. The devices’ architecture is FTO/TiO (blocking layer) TiO (mesoporous)/FAPbIMAPbBr/Spiro-OMeTAD/Au. Notably, low short circuit current (J) was observed at low light intensities (1000 h under real outdoor conditions and the strong ionic component observed at low light irradiation.CN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2013-0295, for the Grants ENE2013-48816-C5-4-R, ENE2016-79282-C5-2-R and the Nanoselect Excelence Network MAT2015-68994-REDC. To the Agència de Gestió d'Ajuts Universitaris i de Recerca for the support to consolidated Catalonia research group 2014SGR-1212 and the Xarxa de Referència en Materials Avançats per a l'Energia (Xarmae). To the COST Action StableNextSol ProjectMP1307. To CONACYT for the PhD awarded to Y.R.Peer Reviewe

Here a physically based channel mobility model has been developed to investigate the temperature dependence of the field-effect mobility of $4H\text{-}\mathrm{Si}\mathrm{C}$ metal-oxide-semiconductor (MOS) transistors with thermally oxidized gate insulators. This model has been designed so that it accounts for the high density of traps at the MOS interface. This temperature dependence is a key issue for silicon carbide electronics, as its basic material properties make it the foremost semiconductor for high power/high temperature electronic devices in applications such as spacecraft, aircraft, automobile, and energy distribution. Our modeling suggests that the high density of charged acceptor interface traps, encountered in thermally grown gate oxides, modulates the channel mobility due to the Coulomb scattering of free carriers in the inversion layer. When the temperature increases, the field-effect mobility of these devices also increases, due to an increase in inversion charge and a reduction of the trapped charge. Experimental data of the field-effect mobility temperature dependence are in good agreement with this model.