Understanding Defects Generated by the Low Temperature Aqueous Synthesis of ZnO

非技术描述：氧化锌单晶薄膜和周期结构具有潜在的应用前景，包括节能发光二极管(LED)、当今S的透明电极？基于GaN合金的数十亿LED产业，以及染料敏化太阳能电池。由于其相对较高的折射率(n=2.05，波长61472 nm)，以及产生2D和3D周期结构的能力，氧化锌已成为限制和引导用于光通信的光的光子晶体应用的重要候选者。作为一种光电材料，它具有宽禁带(~3.4 eV)、激子束缚能是GaN的两倍、高饱和速度、高辐射硬度和高光学透明度。事实上，氧化锌的这些特性中的大多数要么与GaN相似，要么优于GaN，GaN今天是用于LED的材料，已经并将以显著的节能照亮我们的世界。作为一种宽禁带半导体，氧化锌面临着与氮化镓相同的技术障碍，在中村修二于20世纪90年代初做出创新之前--S。由于在性能、原材料可获得性和成本方面的优势，氧化锌有望在价值数十亿美元的固态照明产业中取代GaN。一旦这一技术障碍被克服，这项研究将涉及本科生和研究生。技术细节：将在稳态、平衡的条件下，在基于热力学计算和氧化锌的反向溶解的连续水相反应器中，在低温(&amp；#8804；90°C)中合成氧化锌外延薄膜。(JJ Richardson和FFLange，控制低温水相合成氧化锌，第一部分和第二部分，？晶体生长与设计，9[6]，2570-81(2009))。连续水溶液反应器还被用来合成周期性的2D和3D纳米结构，其尺寸相当于蓝光到红光的波长，具有潜在的光子晶体应用前景。重点研究了合成工艺参数的优化，即pH、温度、氨气浓度、生长速率控制剂的加入。主要目标是利用连续反应堆来了解产生无意n型导电性的点缺陷、由外延核聚合引入的小角度晶界位错以及在250°C热处理过程中观察到的空穴形成。这些了解反过来将被用来优化水相合成的氧化锌的光电性能，以便在带隙工程和有意的n型和p型掺杂方面迈出重要的一步。

NON-TECHNICAL DESCRIPTION: Zinc oxide (ZnO) single crystal films and periodic structures have potential applications that include energy saving light emitting diodes (LEDs), transparent electrodes for today?s multi-billion LED industry based on GaN alloys, and dye-sensitized solar cells. Due to its relatively high index of refraction (n = 2.05, lambda= 500 nm), and the ability to produce 2D and 3D periodic structures, ZnO has become an important candidate for photonic crystal applications that confine and direct the light used for optical communication. As an optical-electronic material, it has a wide band gap (~3.4 eV), an excitonic binding energy twice that of GaN, a high saturation velocity, a high radiation hardness, and a high optical transparency. In fact, most of these properties of ZnO are either similar or superior to those of GaN, which today is the material used for LEDs that has and will light our world at significant energy reduction. As a wide band gap semiconductor, ZnO faces the same technical hurdle as GaN prior to the innovations made by Shuji Nakamura in the early 1990?s. Due to advantages in properties, raw material availability and cost, ZnO is expected to displace GaN in the multi-billion dollar solid-state lighting industry once this technical hurdle is overcome The research will involve undergraduate interns and a graduate student. Emphasis will be placed on selecting underrepresented students.TECHNICAL DETAILS: ZnO epitaxial films will be synthesized, under steady-state, equilibrium conditions, in a low temperature (≤ 90°C) continuous, aqueous reactor that has been constructed based on thermodynamic calculations and the retrograde solubility of ZnO. (JJ Richardson and FF Lange, ?Controlling Low Temperature Aqueous Synthesis of ZnO Part I and II,? Crystal Growth & Design, 9 [6], 2570-81 (2009)). The continuous aqueous reactor has also been used to synthesize periodic 2D and 3D nanostructures, with dimensions equivalent to the wavelength of blue to red light, with potential applications as photonic crystals. The research emphasizes the optimization of synthesis parameters, namely, pH, temperature, ammonia concentration, and additions of rate controlling growth agents. The primary goal is to use the continuous reactor to understand the point defects that produce unintentional n-type conductivity, the dislocations at low angle grain boundaries introduced by the coalescence of epitaxial nuclei, and void formation observed during heat treatments at ≥ 250°C. This understanding will, in turn, be used to optimize the optoelectronic properties of aqueous synthesized ZnO so that significant steps can be taken towards band gap engineering and intentional n- and p-type doping.