GaN nanorod films have been grown on Si(001) substrates with native silicon oxides by radio-frequency plasma-enhanced molecular beam epitaxy. GaN nanorod films are made up of single-crystalline nanorods with a so-called (0001) fiber-like texture. Each nanorod is elongated along c axis in perpendicular to the substrate surface and has no preferential axis in film plane. Excellent electron field emission characteristics were observed for the fabricated GaN nanorod films with a field emission threshold as low as 1.25V∕μm at a current density of 0.1μA∕cm2 and a field emission current density as high as 2.5mA∕cm2 at an applied field of 2.5V∕μm. These excellent characteristics are attributed to the geometrical configuration of nanorods and their good crystalline quality as well as the low electron affinity of GaN.

GaN-based magnetic semiconductors are expected to exhibit ferromagnetism even at high temperatures. We have studied the magnetic and optical properties of transition-metal- and rare-earth-doped GaN. GaCrN showed ferromagnetic characteristics at 7–400 K. Clear hysteresis and clear saturation were observed in the magnetization versus magnetic field (M–H) curves at all measuring temperatures. We observed photoluminescence (PL) emission from GaCrN layers. GaGdN also showed ferromagnetic characteristics at 7–400 K. Sharp PL emission was observed for GaGdN. X-ray diffraction and EXAFS measurements showed no phase separation, and that the Cr and Gd atoms substitute Ga sites. Applications to novel devices controlling charges (electrons and holes), spins and photons are expected.

Articles you may be interested inOptical and magnetic behavior of erbium-doped GaN epilayers grown by metal-organic chemical vapor deposition Appl. Phys. Lett. 91, 054106 (2007);

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Articles you may be interested inGaMnAs-based magnetic tunnel junctions with an AlMnAs barrier Appl. Phys. Lett. 95, 242503 (2009); 10.1063/1.3254218Tunneling magnetoresistance in Ga Mn As ∕ Al As ∕ In Ga As ∕ Al As ∕ Ga Mn As double-barrier magnetic tunnel junctions Appl. Phys. Lett.

We have theoretically studied the magnetotransport properties in bipolar conductors under consideration of the simultaneous presence of an external magnetic field, left–right asymmetric carrier scattering due to spin–orbit interactions, and spin-polarized holes/electrons, predicting both positive and negative transverse magnetoresistance (TMR) terms, the mechanisms of which are completely different from the conventional mechanism in bipolar conductors. The positive TMR term is predicted only for the asymmetric carrier scattering case, the sign of which is the same (negative) between a hole and an electron. The other case of asymmetric scattering, the sign of which is opposite between a hole and an electron, was also determined to always show a negative TMR. Our proposed TMR was experimentally evidenced from the magnetotransport and magnetization measurements of a compensated metal, YH2. Also, application to logic gates is discussed on the basis of our proposed mechanism.

Articles you may be interested inTwo-dimensional ultrashallow junction characterization of metal-oxide-semiconductor field effect transistors with strained silicon