T.L. Chen

p-type conduction in wide-gap Zn1−xMgxO films grown by ultrasonic spray pyrolysis

p-type Zn1−xMgxO films doped with N and Al have been deposited by means of introducing Mg into p-type N- and Al-doped ZnO films using ultrasonic spray pyrolysis (USP) method. The structure of the films is confirmed by x-ray diffraction. Hall-effect measurements indicate that the p-type Zn1−xMgxO film shows a low resistivity of 6.4×10−2Ωcm, high mobility of 11.7cm2∕Vs and high carrier concentration of 8.31×1018cm−3 at room temperature. Furthermore, the optical absorption edge and photoluminescence (PL) peak of p-type Zn1−xMgxO film shift to a shorter wavelength of 356nm while maintaining excellent electrical performances. The blueshift extent of the film based on p-type ZnO film was not as distinct as compared to that of Zn1−xMgxO film based on pure ZnO film, perhaps owing to the variations in the effectiveness of Mg incorporation in the p-type Zn1−xMgxO film and in the Zn1−xMgxO film.

Electrical conduction transition and largely reduced leakage current in aluminum-doped barium strontium titanate thin films heteroepitaxially grown on Ir∕MgO∕Si(100)

Ba0.6Sr0.4Ti1−xAlxO3 (BSTA, x=0, 3 at. %, 6 at. %) thin films have been prepared on Ir∕MgO-buffered silicon substrates by pulsed-laser deposition. All-epitaxial growth of BSTA∕Ir∕MgO∕Si heterostructures has been evidenced by x-ray diffraction and reflection high-energy electron diffraction. A large reduction in the leakage current density of BSTA thin films was observed by aluminum doping. For 3 at. % Al-doped BSTA thin films, the dominant conduction mechanism shows space-charge-limited current behavior at a low electric field, where the trap-filled limit field is determined as ETFL=10KV∕cm, while at a high electric field the Poole–Frenkel emission is operative. In contrast, the conduction mechanism for 6 at. % Al-doped BSTA thin film is dominated by field-enhanced Schottky emission.

RESISTANCE SWITCHING EFFECT OF Ag/Ln1−x CaxMnO3/Pt SANDWICH STRUCTURE

ABSTRACT Ag/Ln1−x CaxMnO3/Pt (Ln = Pr, La, X = 0.3) sandwich structures showing electric-pulse induced reversible resistance switching properties provide a route for a new resistance random access memory (RRAM), because the electric-pulse induced high-resistance state and low-resistance state can be assimilated to logic 1 and 0 in RRAM systems, respectively. In this work the fatigue and the retention behavior of the electric-pulse induced resistance states have been studied. It is found that the retention properties of the EPIR materials can be modified by post-annealing of the materials and by the inner adjusting of the pulse applied mode. Moreover, the EPIR devices can be optimized by initializing using voltage sweep or pulse sweep circles before application to possess the appropriate original resistance and the stable resistance switching behavior.