【作者】 臧晓丹；

【导师】 敬承斌；

【作者基本信息】 青岛科技大学 ， 材料物理与化学， 2010， 硕士

【摘要】 金属Ge材料的制备研究近年来在国内外受到广泛关注,其中包括纳微尺度Ge粒子、纤维和薄膜材料。本论文通过研究六方晶型GeO2粉末与氨水的化学反应,合成出了高浓度、高稳定性的锗酸根离子前驱液。使用还原剂。NaBH4,在室温下还原此锗酸根离子前驱液,合成出了纳微尺度Ge纳米材料,并对各类材料的微观形貌、结构和生长机制进行了研究。通过改变NaBH4与GeO2的比例在相同条件下进行反应,在比例为4-6时获得了结晶性较好的Ge材料。通过不同反应时间和烘干温度条件下的实验发现制得结晶性较好Ge材料的反应时间为12小时以上,烘干温度为120℃。研究发现制备Ge纳米材料的最佳工艺条件为:前驱液中Ge02的浓度为3%。NaBH4/GeO2摩尔比为5,还原时间24小时,120℃烘干。NaBH4还原锗酸根离子前驱液12小时得到的Ge粒子为球型(20-50 nm),24小时为蠕虫状。粒子此形状的变化符合奥斯瓦尔德熟化机制。以NaBI-14还原锗氨溶液所得氢化的Ge溶胶为原料,通过干燥和蒸镀可以得到致密Ge薄膜材料。薄膜由直径在100纳米左右的粒子组成。随着蒸发温度的升高,致密Ge薄膜中粒子的结晶性随之提高,薄膜厚度增加。Ge薄膜的拉曼光谱在300 cm-1左右有一个尖锐的峰,对应着晶态Ge的,在265-270 cm-1左右有一个强度较弱的峰,对应着非晶态的Ge,随着蒸镀温度的升高非晶峰逐渐消失,与XRD结果相一致。Ge薄膜材料由325nm波长激发产生的发光峰主要集中在693nm到835 nm之间,峰的最高点位于753 nm左右。Ge薄膜的拉曼和荧光性质与纯Ge单晶不同,是由Ge薄膜生长时形成的缺陷和晶格内应力效应引起的。我们所制备的Ge薄膜为p型半导体,空穴浓度的数量级为1023cm-3,迁移率为60cm2.V-1.s-1。更多还原

【Abstract】 The fabrication of germanium materials including Ge nanocrystals and Ge thin films has attracted much more attention recently. In this work, stable germanate ion aqueous solution with high solid content was synthesized through interaction between hexagonal GeO2 powders and aqueous ammonia. A reducing agent NaBH4 was used to reduce GeO2 solute into nano crystalline Ge. Ge thin films were obtained by evaporating the hydrogenated Ge nano products. The morphologies, structures and growth mechanisms of these materials were investigated.The molar ratio of NaBrVGeO2 under which crystalline Ge products can be obtained is from 4 to 6. The reaction time and drying temperature are no less than 12 hours and 120°C, respectively. The best reaction conditions for synthesis of crystalline Ge products are as follows: The GeCh content of the germanate ion precursor is 3%, NaBH4/GeO2 molar ratio is 5, reaction time 24 hours and drying temperature 120°C. When the reaction time is 12 hours, the Ge nano samples consist of sphere-shape Ge nano particles (20-50nm). Worm-like crystallined Ge product was obtained as the reaction time remains 24 hours. The growth mechanism of the products follows Ostwald Ripening mechanism.Ge films could be prepared by evaporating hydrogenated Ge sol that was synthesized by interaction between NaBH4 and germanate ion aqueous solution. The films are composed of Ge nanoparticles with size of about 100 nm. The degree of crystallinity and thickness of the films increases with rising temperature. There is a sharp peak corresponding to crystalline Ge at about 300 cm-1 and an amorphous shoulder at 265-270 cm’1 in the Raman spectrum of the Ge film. The amorphous peak disappears gradually with increasing temperature, which is consistent with the XRD results. Photoluminescence (PL) peaks centralize at 693-835 nm. The strongest PL peak appears at 753 nm under excitation with 325 nm light. The observed Raman and PL are different from that of a single crystal Ge, which likely originates from the compressive strain in the crystal lattices. The Ge films are p-type and their hole densities are in the order of magnitude of 1023 cm-3 The average mobility of carrier is about 60 cm2.V更多还原