During the past years, the investigations for Diluted Magnetic Semiconductor (DMS) nanomaterials have attracted considerable attention due to their novel properties and broad application prospects in diverse areas, such as logic devices, spin polarized light emitting diode, spin field-effect transistors, field-emission devices, optical isolator, non-volatile memory devices and quantum computer,...

Unidirectional electric current flow, such as that found in a diode, is essential for modern electronics. It usually occurs at asymmetric interfaces such as p-n junctions or metal/semiconductor interfaces with Schottky barriers. We report on a diode effect associated with the direction of bulk electric polarization in BiFeO3: a ferroelectric with a small optical gap edge of approximately 2.2 el...

A strong superconducting diode effect (SDE) is revealed in a thin film periodically nanostructured with magnetic dots. The SDE caused by the current-activated dissipation mitigated vortex-antivortex pairs (VAPs), which nucleate under dots, move and annihilate superconductor - eventually driving system to high-resistive state. Inversing polarity of applied current destimulates nucleation VAPs, r...

In this paper, the general characteristics and the scalability of Schottky barrier metal-oxide-semiconductor field effect transistors (SB-MOSFETs) are introduced and reviewed. The most important factors, i.e., interface-trap density, lifetime and Schottky barrier height of erbium-silicided Schottky diode are estimated using equivalent circuit method. The extracted interface trap density, lifeti...

While science has good knowledge of semiconductor bandgaps, there is not much information regarding the steepness of the band-edges. We find that a plot of absolute conductance, I/V versus voltage, V, in an Esaki diode or a backward diode will reveal a best limit for the band tails, defined by the tunneling joint density of states of the two band-edges. This joint density of states will give in...

Several types of nanofluidic devices based on nanopores and nanochannels have been reported to yield ionic current rectification, with the aim to control the delivery of chemical species in integrated systems. However, the rectifying properties obtained by existing approaches cannot be altered once the devices are made. It would be desirable to have the ability to modulate the predefined proper...

Charge and potential profiles are self-consistently calculated in double-barrier heterostmctures to derive the capacitance of resonant tunnelling devices. We show that the dipole charge integrated over the accumulation or the depletion side of the device is the result of a complex arrangement of the mobile charge dragged and drifted when a bias is applied. Excellent agreement is found with capa...

introduction: laser irradiation has been introduced in endodontic treatment due to its bactericidal effect. the aim of this study is to evaluate the bactericidal efficacy of a 940 nm diode laser alone or in combination with 5% sodium hypochlorite (naocl) against mature biofilms of e. faecalis . methods: sixty-eight (60 for the three groups, 4 for sem and 4 as negative controls) single-rooted hu...

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Heikki Holmberg Name of the dissertation Spin-dependent transport in Mn Doped GaAs and GaN diodes Manuscript submitted 16.11.2007 Manuscript revised 4.2.2008 Date of the defence 14.3.2008 Monograph Article dissertation (summary + original articles) Faculty Faculty of Electronics, Commu...