The Ag/TiO2/Nb:SrTiO3/Ag device exhibits the coexistence of electric field controlled ferromagnetism and resistive switching at room temperature. The bipolar resistive switching in Ag/TiO2/Nb:SrTiO3/Ag device may be dominated by the modulation of Schottky-like barrier with the electron injection-trapped/detrapped process at the interface of TiO2/Nb:SrTiO3. We suggest that the electric field-induced magnetization modulation originates mainly from the creation/annihilation of lots of oxygen vacancies in TiO2.

Amorphous indium-gallium-zinc oxide (a-InGaZnO or a-IGZO) has already started replacing amorphous silicon in backplane driver transistors for large-area displays. However, hardly any progress has been made to commercialize a-IGZO for electronic circuit applications mainly because a-IGZO transistors are not yet capable of operating at GHz frequencies. Here, nanoscale a-IGZO thin-film transistors (TFTs) are fabricated on a high-resistivity silicon substrate with a Ta2O5 gate dielectric. Carrier mobilities up to 18.2 cm 2 V-1 s-1 have been achieved. By optimization of the TFT channel length and contact overlap, we are able to demonstrate current-gain and power-gain cutoff frequencies at 1.24 and 1.14 GHz, respectively, both beyond the 1 GHz benchmark. Such a performance may have implications in developing at least medium-performance, a-IGZO-TFTs-based circuits for low-cost or flexible electronics.

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A surface passivation technique has been developed for AlGaN/AlN/GaN high electron mobility transistors (HEMTs) by simple thermal evaporation of silicon monoxide (SiO) at room temperature. Detailed device characteristics were studied and compared with the most commonly used SiN x passivation grown by plasma enhanced chemical vapor deposition at elevated temperatures. Both passivation techniques lead to similar enhancement in on-state drain current and transconductance as compared with the unpassivated HEMTs. However, we discovered that the gate leakage current in SiO passivated devices was more than two orders of magnitude lower than the devices passivated by SiN x . Furthermore, while SiN x passivated HEMTs exhibited a two orders of magnitude increase in off-state drain current, SiO passivation substantially reduced it, resulting in an overall improvement by a factor of 1429.The extent of device surface damage caused by passivation was also investigated by characterizing other parameters. The subthreshold slope of SiO passivated HEMTs was 95 mV·dec -1 , nearly 5 times better than SiN x passivated devices. The extracted interface trap density was 1.16×10 12 cm -2 eV -1 , about ten times lower than that in SiN x passivated HEMTs.Moreover, SiO passivation was found to enhance the gate Schottky barrier height by 60 meV whereas SiN x passivation reduced it, which could partially explain the differences in gate leakage current. Finally, SiO passivation enabled twice high breakdown voltage than SiN x passivation. The relevant physical mechanisms were discussed.

Electrically induced resistive switching and modulated ferromagnetism are simultaneously found in a Ag/HfO2/Nb:SrTiO3/Ag resistive random access memory device at room temperature. The bipolar resistive switching (RS) can be controlled by the modification of a Schottky-like barrier with an electron injection-trapped/detrapped process at the interface of HfO2-Nb:SrTiO3. The multilevel RS transition can be observed in the reset process with larger negative voltage sweepings, which is connected to the different degree of electron detrapping in the interfacial depletion region of the HfO2 layer during the reset process. The origin of the electrical control of room-temperature ferromagnetism may be connected to the change of density of oxygen vacancies in the HfO2 film. The multilevel resistance states and the electric field controlled ferromagnetism have potential for applications in ultrahigh-density storage and magnetic logic device.