We suggest a phenyl-C₆₁-butyric acid methyl ester (PCBM)-blended chlorobenzene (CBZ) hybrid anti-solvent washing technique for the morphological control of perovskite films. Compared to standard CBZ washing, the CBZ + PCBM hybrid washing technique endows perovskite films with a pinhole-free and compact surface morphology. Surface topography combined with phase imaging using atomic force microscopy showed that PCBM could fill up the voids and pinholes on the perovskite surfaces. Inverted planar perovskite solar cells processed using this new approach exhibited an impressive increase in the average fill factor from 0.583 to 0.747 for 40 tested devices by reducing charge recombination through the pinholes, which also contributed to an enhancement of the power conversion efficiency of the best performing cells of about 16.1% (from 9.48 to 11.01%). Furthermore, the fabricated devices showed negligible hysteresis phenomena. The presented results suggest a new and simple approach that reinforces the feasibility of low-temperature-processed inverted planar perovskite photovoltaics with enhanced performances.

In this study, degradation phenomena due to gate bias stress at elevated temperature for the reliability test of punch-through IGBTs, which are widely used in DC circuit systems for automotive applications, were investigated. For the reliability tests of various temperatures, 4000 times temperature cycle stress was applied in IGBTs between -40 oC and 200 oC to accelerate the degradation process using the wide range temperature. And the delamination of the passivation layer and the metal layer in IGBTs was observed using the scan acoustic microscopy. In addition, the positive bias stress with 48 V at elevated temperature of 150 oC for 60 min was applied to the gate, the threshold voltage increased up to 6.07 V due to charge trapping at gate oxide. We also compared the recovery of the devices, but the IGBTs that stressed with high DC field and elevated temperature slowed down the recovery process after 24 hours without reverse voltage. This work was focused to find the device recovery considering real conditions. Therefore, the various temperature stress and high electric field stress are important in the reliability test for IGBTs, it was reported the IGBT degradation process and failure symptoms using the accelerated and various reliability tests.

The effects of nitride-based plasma pretreatment on the output characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) on silicon substrates are investigated. N₂ and NH₃ plasma pre-treatment methods are studied to overcome the RF dispersion phenomenon caused by nitrogen-vacancy (V_N)-related defect reduction. It is found that the nitride-based plasma pretreatment is effective to overcome the RF dispersion in AlGaN/GaN HEMTs on Si. The NH₃ plasma pretreatment markedly reduced RF dispersion from 63 to 1%. This is considered to be attributable to the reduction of the effective V_N-related defect density and elimination of carbon/oxide residuals on the surface of AlGaN/GaN HEMTs. A NH₃ plasma pretreatment prior to SiN _x 100 nm passivation in the AlGaN/GaN HEMTs on Si markedly improves the total output power from 15 to 18.1 dBm under the operating conditions of V _DS = 15 V/V _GS = -1 V.