Suppression Of Electron Injection Research Articles

Schottky Source/Drain InAlN/AlN/GaN MISHEMT With Enhanced Breakdown Voltage

In this letter, we present the deployment of Schottky source/drain (SSD) in InAlN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs) for off-state breakdown voltage improvement. The improved breakdown voltage relies on the suppression of electron injection into the buffer under the Schottky source contact. A <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BD</sub> of 460 V is obtained in an SSD MISHEMT with an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GD</sub> = 10 μm, at a 170% improvement compared with that of the control MISHEMT featuring ohmic source/drain. Despite the SSD contacts, an SSD MISHEMT with a gate length of 1 μm exhibits a respectable drain current density of 416 mA/mm and a transconductance of 113 mS/mm.

Electroluminescent properties of organic light-emitting diodes using BAlq and Alq 3 co-evaporation layer

We applied co-evaporation films (BAlq:Alq 3) as an emission layer of OLED and studied their energy carrier transfer process. Energy was partially transferred from excited BAlq to Alq 3 by PL spectra. We also investigated its light-emission mechanism using a co-evaporation layer in OLED. Energy transfer occurs from NPD to Alq 3 or suppression of electron injection into NPD takes place. Furthermore, the hole is injected into the BAlq within 20-nm distance from the NPD/BAlq interface injected holes can move to as much as 10 nm from the interface. Doping Alq 3 in BAlq changes the number of electrons that are injected into BAlq because of its electron trapping against BAlq. We also suggest that the rate constant of energy transfer from NPD to Alq 3 is shorter than the radiative deactivation time of NPD. The number of NPD excitons generated by recombination is less than that of deactivating Alq 3.

Suppression of electron injection into a finite superlattice in an applied magnetic field

We present experimental and theoretical studies of the current-voltage characteristics, $I(V),$ of undoped $\mathrm{GaAs}/({\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x})\mathrm{As}$ superlattices (SL's) in a strong magnetic field $\mathbf{B}$ applied parallel to the growth axis. A series of $I(V)$ characteristics measured at $B=1,2,\dots{},10 \mathrm{T}$ shows that increasing the magnetic field gradually suppresses the current across the whole range of V. We show that at low V this suppression originates from a decrease in the rate of injection of carriers into the SL from the heavily doped emitter contact. Because the chemical potential in the emitter contact lies below the lowest miniband of the SL, electrons enter the SL by tunneling through a triangular potential barrier formed by the miniband edge. The tunneling rate depends on V and on the electron energy for longitudinal motion along the SL axis. The latter is reduced (by at least $\ensuremath{\Elzxh}{\ensuremath{\omega}}_{c}/2,$ where ${\ensuremath{\omega}}_{c}$ is the cyclotron frequency) in the magnetic field. Consequently, the tunneling rate decreases with increasing $\mathbf{B}.$ This mechanism of suppression dominates at low voltages $(Vl40 \mathrm{mV})$ when the barrier transmission coefficient is low.