Presence Of Minority Carriers Research Articles

Indium‐Doped Silicon for Solar Cells—Light‐Induced Degradation and Deep‐Level Traps

Indium‐doped silicon is considered a possible p‐type material for solar cells to avoid light‐induced degradation (LID), which occurs in cells made from boron‐doped Czochralski (Cz) silicon. Herein, the defect reactions associated with indium‐related LID are examined and a deep donor is detected, which is attributed to a negative‐U defect believed to be InsO2. In the presence of minority carriers or above bandgap light, the deep donor transforms to a shallow acceptor. An analogous transformation in boron‐doped material is related to the BsO2 defect that is a precursor of the center responsible for BO LID. The electronic properties of InsO2 are determined and compared to those of the BsO2 defect. Structures of the BsO2 and InsO2 defects in different charges states are found using first‐principles modeling. The results of the modeling can explain both the similarities and the differences between the BsO2 and InsO2 properties.

Electron-beam-induced migration of hydrogen in Mg-doped GaN using Eu as a probe

We demonstrate the use of hydrogen induced changes in the emission of isoelectric Eu ions, in Mg-doped p-type GaN, as a powerful probe to study the dynamics of hydrogen movement under electron beam irradiation. We identify, experimentally, a two-step process in the dissociation of Mg-H complexes and propose, based on density functional theory, that the presence of minority carriers and resulting charge states of the hydrogen drives this process.

Improved Observation of SiC/SiO<sub>2</sub> Oxide Charge Traps Using MOS <i>C-V</i>

We have used C-V techniques to study the bias instability of 4H-SiC MOS capacitors and FETs, and compared those results to those obtained using ID-VGS. The net “back-and-forth” instability from C-V was found to exceed that of ID-VGS and matched closely with values from fast ID-VGS and midgap extrapolation, suggesting that the C-V method is more effective at measuring a “true” instability effect than ID-VGS alone. Using C-V, capacitors and large-area MOSFETs showed similar instability behavior, implying that the presence of minority carriers are not necessary to observe bias instability. One-way bias-stress C-V measurements reveal that most of the bias instability occurs under negative bias stress, whereas the opposite is observed in one-way bias stress ID-VGS measurements. Finally, post-oxidation NO annealing reduced the ΔVT bias instability for positive bias stress but does not appear to have influenced any of the other conditions.

Minority-carrier-enhanced dissociation of the boron–hydrogen pair in silicon

Abstract The depth profiles of the boron–hydrogen pairs and their variations due to thermal treatments in the dark and under photoexcitation are studied in the p-type silicon crystal. The presence of minority carriers is observed to increase the dissociation rate of the BH pairs by two orders of magnitude at 310 K. The effect is attributed to recharging of the partially dissociated hydrogen atoms.

Near-field scanning optical microscopy of cleaved vertical-cavity surface-emitting lasers

Near-field scanning optical microscopy (NSOM) and near-field optical spectroscopy (NFOS) techniques have been applied to cleaved vertical-cavity surface-emitting lasers (VCSELs). Collection mode NSOM of the cleaved VCSEL operating above the threshold current indicates emission outside the active layer. Using the spatially resolved spectroscopy afforded by NFOS, it was possible to map changes in the electroluminescence spectrum with spatial resolution of the order of 100 nm . The emission spectra acquired with the tip positioned over the p-DBR layers show evidence for p-DBR luminescence. The p-DBR luminescence indicates the presence of minority carriers in this region of the device which have been postulated as a cause of dark line defects (DLDs) which play an important role in device degradation.

Minority-carrier-enhanced reactivation of hydrogen-passivated Mg in GaN

The influence of minority-carrier injection on the reactivation of hydrogen passivated Mg in GaN at 175 °C has been investigated in p-n junction diodes. The dissociation of the neutral MgH complexes is greatly enhanced in the presence of minority carrier and the reactivation process follows second-order kinetics. Conventional annealing under zero-bias conditions does not produce Mg-H dissociation until temperatures ≥450 °C. These results provide an explanation for the e-beam-induced reactivation of Mg acceptors in hydrogenated GaN.