ZnO is one of the most investigated wide band gap metal oxide, which finds its successful applications in optoelectronics, such as light emitting devices, photovoltaics, photodetectors, and field emission. The formation of nanowires enables charge separation between the nanowire center and the surface, the enhanced carrier lifetime and consequently much increased light responsive for high sensitivity photodetector applications . Mg<SUB>x</SUB>Zn<SUB>1-x</SUB>O alloys are broadly studied as solar blind photodetectors for military and aerospace applications. By increasing the Mg atomic fraction to x~0.44, the bandgap can be around 4.2eV, leading to the solar blind region. However, crystal phase segregation between ZnO and MgO was observed for Mg concentrations x>0.36, due to the different crystal structures and large lattice mismatch between hexagonal ZnO and cubic MgO . On the other hand, the value of the energy band gap of BeZnO can be efficiently engineered to vary from the ZnO band gap (3.4eV) to that of BeO (10.6eV) . Both ZnO and BeO are hexagonal crystal structure and the a-axis lattice constant values for ZnO and BeO are 3.249 and 2.698 Å, respectively, which is much less than the MgO and ZnO case.
In this study, we report our research progress on low temperature synthesis of Be<SUB>x</SUB>Zn<SUB>1-x</SUB>O nanorods from a mixture solution of beryllium and zinc salt. Similarly to hydrolysis of zinc acetate with addition of hexamethylenetetramine (HMTA, weak base) for Zn nanowire growth, beryllium nitrate forms tetrahedral beryllium hydroxide with addition of alkalis which is soluble in excess of hydroxide ions thermally released from HMTA. Then, decomposition of Be(OH)<SUB>2</SUB> and Zn(OH)<SUB>2</SUB> in aqueous solution forms BexZn1-xO alloy, where the Be concentration is controlled by the initial Be salt concentration in the solution. Two seeding process are studied: 1) decomposing of beryllium nitrate and zinc acetate alcohol solution at temperature higher than 250°C in Ar/N<SUB>2</SUB> environment produces BeO and ZnO textured seeds  for BeZnO nanorods to grow; 2) we also tested is using different materials as seeding layer (ZnO, Au and ITO) on SSP c-sapphire substrates. The optical transmission measurement of nanorods array is studied using iHR550 spectrometer mounted with UV enhanced Xenon arc lamp. Bandgap of synthesized nanorods is measured using photoluminescent (PL) excited using 230 nm UV source and also directly calculated from (<I>αhν</I>)<SUP>2</SUP> vs. <I>hν</I> plot , where <I>α</I> is the absorption coefficient with respect to average length of nanorods. Since Be has light atoms, its concentration is then determined from the bandgap. Due to the limit of current UV light source (lowest wavelength 240nm), theoretically the maximum Be concentration that can be measured is x<0.4. Additionally, higher decomposition temperature (>110°C) is realized by modifying the Ethylene glycol concentration in water. To further improve the aspect ratio of the nanorods, surfactant (Polyethylenimine Mw~800) effect  is also investigated.