A wide-band gap oxide alloy, BeZnO, is proposed and studied in this letter. The BeZnO films were deposited on sapphire substrates by our hybrid beam deposition growth method. The value of the energy band gap of BeZnO can be efficiently engineered to vary from the ZnO band gap ͑3.4 eV͒ to that of BeO ͑10.6 eV͒. BeZnO can be used for fabricating films and heterostructures of ZnO-based electronic and photonic devices and for other applications. Changes in the measured energy band gap and lattice constant values with Be content are described for BeZnO alloys.
We report fabrication of homostructural ZnO p–n junctions that contain arsenic (As)-doped ZnO (ZnO:As) and intrinsic n-type ZnO layers. We also describe the metallization process for forming ohmic contacts to p-type ZnO. ZnO films were synthesized on n-type SiC substrates by hybrid beam deposition. Ni/Au metal contacts show linear I–V characteristics indicative of ohmic behavior, while other metal contacts (e.g., In/Au and Ti/Au) show nonlinear characteristics with rectification that reveal the presence of Schottky barriers. The characteristics for p–n junctions composed of ZnO layers are confirmed by I–V measurements.
The p-type GaN epilayers were prepared by metalorganic chemical vapor deposition and subsequently Mn+ ions implanted. The properties of Mn+ ions-implanted GaN epilayers were investigated by optical and magnetic measurements. The results of photoluminescence measurement show that optical transitions related to Mn apparently appear at 2.5 eV and around 3.0 eV. It is confirmed that the photoluminescence peak at 2.5 eV is a donor–Mn acceptor transition. Ferromagnetic hysteresis loop was observed, and the temperature-dependent magnetization displayed a ferromagnetic behavior persisting up to ∼270 K.
The crystalline properties of Be substituted ZnO(BeZnO) films deposited on c-Al2O3 substrates are studied. As Be concentration in BeZnO increases, the lattice parameters of BeZnO increases; the c-axis lattice is more sensitively shifted than the a-axis lattice. The energy band gap of the BeZnO films has been efficiently modulated from 3.38eV to 3.81eV by adding Be into ZnO. A linear dependency between band gap and lattice parameters is observed from BeZnO films. BeZnO alloys can be used for new ZnO-based devices based on double heterostructures, quantum wells, or superlattices made with ZnO and BeZnO.
We report on the formation of ohmic contacts to As-doped ZnO layers using a Pt/indium tin oxide ͑ITO͒ scheme. The As-doped ZnO layer shows p-type conductivity with carrier concentrations of 5.12-9.74ϫ10 16 cm −3 when annealed at 25-400°C for 1 min in nitrogen ambient. However, the ZnO layers exhibit n-type characteristics with carrier concentration ca.10 18 -ca.10 19 cm −3 when annealed at 500-800°C. The Pt/ITO contacts produce contact resistivities of 8.0ϫ10 −4 − 3.5ϫ10 −3 ⍀ cm 2 upon annealing at 300-600°C. Possible ohmic formation mechanisms for the Pt/ITO contacts to the As-doped ZnO layers are described and discussed.
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