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An efficient polymer light-emitting diode (PLED) was fabricated by inserting polyurethane (PU) between a poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) layer and an Al cathode. The electroluminescence (EL) efficiency of the PU-based device can reach 1.27 cd/A, which is much higher than that of a device without PU (0.015 cd/A). The enhanced performance is attributed to both the hole-blocking capacity of the PU layer and the specific interaction between PU and the deposited Al, significantly facilitating the injection of electrons. Furthermore, the electron injection ability of PU-based devices was found to strongly depend on the thicknesses of the PU and Al layers.

The effect of electron injection in polymer light-emitting diodes has been investigated at the interface between the CsF layer and metals of the cathode. Efficient electron injection was achieved when the thickness of the CsF layer deposited on the organic layer was 1.5 nm. When the thickness of the MgAg layer deposited on the CsF layer was more than 1 nm, efficient electron injection was achieved. For the device with a 1.5-nm-thick CsF and a 1-nm-thick MgAg cathode, the deposition orders of CsF and MgAg were independent of efficient electron injection. That is, the coexistence of CsF and MgAg near the organic layer resulted in efficient electron injection. To achieve efficient electron injection, we found that was sufficient device performance was obtained when the surface of the organic layer with CsF was covered with approximately 25% MgAg.

We have investigated the layered manganite La0.5Sr1.5MnO4 surface at 100 K by scanning tunneling microscopy (STM). The surface roughness at 100 K below the charge and orbital order transition temperature (TCO = 220 K) is less than that at room temperature. By electron injection from the tip, STM measurements generate protrusions of about 2.5 nm diameter and 0.3 nm height in the scanned area on the surface. The induced protrusions at 100 K are aligned along the specific crystallographic directions, [100] or [010], whereas those at 300 K are randomly distributed.

The performance of n-type field-effect transistors (FETs) using naphthalene tetracarboxylic dianhydride (NTCDA) was improved by inserting an electron injection layer consisting of indium-doped NTCDA at the source electrode interface. This film had very high conductivity due to electronic interactions between carbonyl oxygens and indium. The insertion of the indium-doped NTCDA film increased field-effect mobility and reduced threshold gate voltage. Injection enhancement was confirmed separately using a sandwich-type layered cell having the same interface as that of the FET device. The role of the injection layer is discussed in terms of contact resistance in n-type organic FETs.

The suppression of the current collapse phenomenon is required for reducing on-resistance in AlGaN/GaN high-electron-mobility transistors. Current collapse is caused by electron trapping at the surface and in the buffer layer. In previous works, electron injection to traps has been mainly regarded as being due to gate leakage current; however, other factors have not been discussed. In this study, a novel current collapse mode induced by source leakage current is examined with a 2D device simulator. In addition to gate leakage current, electron trapping is induced by source leakage current that flows under the gate electrode during the off-state. The electron trapping increases on-resistance and decreases pinch-off voltage. The increase in on-resistance is clarified under several trap and voltage conditions. In the simulated range, it is revealed that the on-resistance increases over 1.31 times by the source current collapse mode only, when the stress drain voltage of 500 V is applied during the off-state.

The promising use of non-overlapped implantation (NOI) n-type MOSFETs as nonvolatile memory (NVM) devices has received considerable interest owing to their simple device structure and compatibility with logic CMOS processing. In NOI n-type MOSFETs, the charge distribution by channel hot electron injection (CHEI) programming markedly differs from that in other charge trapping devices in terms of electron injection distribution. In this study, hot hole injection (HHI) in NOI NVM devices is investigated using Technology Computer Aided Design (TCAD) simulations, measured program/erase speeds, and charge pumping (CP) techniques. Furthermore, HHI efficiency is theoretically deduced and compared with that of silicon–oxide–nitride–oxide–silicon (SONOS) devices. Similar to the results for SONOS device, the lateral fields by VD biases significantly enhance HHI for erasing NOI devices. However, preprogrammed electrons are also dominant in erasing NOI devices. On the basis of the CP results, the hole distribution by HHI in NOI NVM devices strongly correlates with the distribution of preprogrammed electrons.

The current transport characteristics of quasi-Al x Ga1-x N/SiC heterojunction bipolar transistors (HBTs) with various band discontinuities were investigated in a low-current range using a Gummel plot. In the low-current range, the base currents of the HBTs were dominated by recombination currents. The collector current characteristics of the HBTs in the low-current range were almost the same in spite of the various band discontinuities, and the ideality factor n was 1.0. The band discontinuities at the heterojunction had no effect on electron injection in the low-current range. This is because the collector currents were dominated by diffusion process in the base region rather than by injection process at the AlGaN/SiC interface.

Electron injection and the transport properties of three phenazine compounds, tetrabenzophenazine (TBP), dibenzodipyridophenazine (DBDPP), and tetrapyridophenazine (TPP), were investigated to determine the effect of nitrogen atoms in fused-ring molecules. These three compounds worked as electron transport materials, exhibiting high electron mobility – on the order of 10-3 cm2 V-1 s-1. Increasing the number of nitrogen atoms deepened the energy levels and lowered crystallinity in vacuum-deposited films. In particular, TPP containing six nitrogen atoms showed very efficient electron injection from an aluminum cathode.

In this work, KBH4 was studied as a novel electron injection material (EIM) for organic light-emitting diodes (OLEDs). Optimized OLEDs using KBH4 as the EIM showed a high efficiency of 11.0 cd/A at 1000 cd/m2, comparable to that of a control device using LiF (9.2 cd/A). The lifetime of the device with KBH4 was also comparable to that of the control device. Thermal evaporation behavior was studied by thermodynamic calculation and X-ray photoemission spectroscopy (XPS), demonstrating that the improved electron injection was attributable to the low-work-function metallic K released by the thermal decomposition of KBH4.

We demonstrate that benzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX) derivatives show high-efficiency carrier injection in organic light-emitting diodes (OLEDs). Using 3,11-dibromobenzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX6) as a hole injection layer (HIL), we achieved a low driving voltage of 8.12±0.10 V in obtaining a current density of J=100 mA/cm2. The hole injection characteristics were superior to those of a device with a conventional CuPc layer as a HIL. On the other hand, inserting benzo[1,2,3-kl:4,5,6-k'l']dixanthene (BDX1) as an electron injection layer (EIL) efficiently decreased driving voltage, indicating a superior electron injection capability compared with a device without a BDX1 EIL. We show that carrier injection efficiency can be well controlled by the substituent groups of BDX, thus providing efficient hole and electron injection layers.

We have used the cyclic current–voltage (I–V) technique to characterize border traps generated by Fowler-Nordheim tunnel (FNT) electron injection in metal-oxide-semiconductor (MOS) capacitors. We clarified that the current components measured from as-grown samples by the cyclic I–V technique are directly related to the formation or removal of an inversion layer, and we refer to such data as the background current. On the contrary, the distinct peaks in the I–V curves were developed in addition to the background current after generating border traps by FNT electron injection. We suggest that the peaks were caused by the reversible charge-exchange between border traps and underlying Si via donor-like interface traps located near the 0.35 eV above the valence band edge.

We have investigated the relationship between electroluminescent (EL) device performance and electron injection properties on the basis of the Schottky emission model. The EL device with dithienosilole derivatives (DTS) as an electron injection layer has a lower energy barrier (0.33 eV) for electron injection from magnesium compared to that (0.43 eV) of a typical EL device without DTS. This may lead to the improvement in the electrical properties of the EL device with DTS.

Physical mechanisms responsible for the operation and performance of Multiple Quantum Well (MQW) infrared photodetectors are studied using computer modeling. It is shown that the operating mechanism of MQW infrared photodetectors is associated with the redistribution of the potential across an MQW structure under the influence of absorbing radiation, which, in turn, results in the stimulation of electron injection from the emitter contact into the MQW region. The distribution of the electric field under the applied bias is highly nonuniform, with two distinct domains of high field, which controls the electron injection, and low field, supporting the transport of the injected electrons.

The correlation between the passivation film formation for InP/InGaAs heterojunction bipolar transistors and transistor current-voltage (I-V) characteristics is investigated. The I-V characteristics vary significantly depending on the kind of passivation films. The major change in I-V characteristics is the increase in base current (I b),which implies the generation of an additional recombination process around the surface of the emitter-base junction. A change in collector current (I c) is also observed, indicating that the electron injection mechanism changed near the passivated semiconductor surface. These surface currents are produced by the interaction of the semiconductor surface with the passivation films. It is shown that these surface currents are greatly suppressed using a buffered hydrofluoric acid solution before the passivation film formation.

The role of interfacial states in the electroluminescence process for Ta-Ta2O5-ZnS: Tb3+-Au and Ta-Ta2O5-ZnS: Tb3+-SiO2-Au structures has been studied. A similar electroluminescence has been observed for both types of cells. This indicates that electron injection via tunneling from the Au contact is not necessarily required to produce electroluminescence. The relaxation times of electrons related to the injection process from interfacial states are measured to be 10–100 ms. These values are the same for three interfacial states of interest (ZnS-Au, ZnS-SiO2 and ZnS-Ta2O5). Their temperature and electric field dependences are also presented. It can be concluded that field emission from the interfacial states is essential to the electron injection process for these types of cells.

Effect of bias application on capacitance-voltage (C-V) characteristics in metal-aluminum oxide-(silicon dioxide)-silicon (MA (O) S) structures is investigated. Broadening or distortion of C-V characteristics is often observed after a negative bias application to the electrode. Change of C-V characteristics with applied negative bias voltage is divided into four regions related to the partial injection of electrons and holes into the film. Electron injection into the film depends on the properties of the electrode-aluminum oxide film interface, and holes are injected in amount corresponding to the magnitude of the electric field changed by the distribution of electrons stored in the film.