溶胶-凝胶法制备Li-N双掺p型ZnO薄膜的结构、光学和电学性能

采用溶胶-凝胶法在n型Si(100)衬底上沉积Li-N双掺杂ZnO薄膜,经X射线衍射和扫描电镜图片分析,所制备薄膜具有多晶纤锌矿结构和高的c轴择优取向.室温下霍尔效应测试结果显示Li-N双掺杂ZnO薄膜具有p型导电特性.在Li掺杂量为15.0at%,Li/N（摩尔比）为1∶1,700℃退火等优化条件下得到的最佳电学性能结果是：电阻率为0.34 Ω·cm,霍尔迁移率为16.43 cm²/V·s,载流子浓度为2.79×10¹⁹ cm^{-3关键词： Li-N双掺 p型ZnO薄膜 溶胶-凝胶 性能}     

离子束增强沉积制备p型氧化锌薄膜及其机理研究

采用离子束增强沉积方法在Si和SiO₂/Si衬底上制备In-N共掺杂ZnO薄膜(INZO)，溅射靶是用ZnO和2 atm% In₂O₃粉体均匀混合并压制而成，在氩离子溅射ZnO靶的同时，氮、氩混合离子束垂直注入沉积的薄膜.实验结果显示INZO薄膜具有(002)的择优取向，并且为p型导电，电阻率最低为0.9Ωcm.薄膜在氮气、氧气气氛下退火，对薄膜的结构和电学特性与成膜和退火条件的关系进行了分析. 关键词： 氧化锌薄膜 p型掺杂 离子束增强沉积     

高浓度Er/Yb共掺ZnO薄膜的结构及室温光致发光特性

采用射频磁控溅射方法制备了Er/Yb共掺ZnO薄膜,研究了退火处理对高浓度Er/Yb共掺ZnO薄膜的结构演化和光致发光(PL)特性的影响。X射线衍射分析结果表明:Er/Yb掺杂导致ZnO薄膜的晶粒细化及择优取向性消失,ZnO晶粒随退火温度的增加而逐渐长大。900℃退火时,出现Er3 、Yb3 偏析,退火温度高于1000℃时,薄膜与基体间发生了界面反应,1200℃时,ZnO完全转变为Zn2SiO4相。光致发光测量结果表明:高于900℃退火处理后,Er/Yb共掺ZnO薄膜在1540 nm附近具有明显的光致发光,发光强度在退火温度为1050℃时达到最大值;光致发光光谱呈现典型的晶体基质中Er3 离子发光光谱所具有的明锐多峰结构特征。此外,探讨了薄膜结构演化及其对光致发光光谱的影响。     

Zn1-xMgxO薄膜p型导电和光学性能

采用超声喷雾热分解(Ultrasonic Spray Pyrolysis,USP)方法,以醋酸锌、醋酸镁、醋酸铵、氯化铝的混合水溶液为前驱溶液,在单晶Si(100)衬底上制备了ZnO,Zn_0.81Mg_0.19O,N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜。以X射线衍射(XRD)、场发射-扫描电镜(FE-SEM)、霍尔效应(Hall-effect)、光致发光(Photoluminescence,PL)谱等手段研究了薄膜的晶体结构、表面形貌、电学性能、光学性能和带隙变化。电学测试结果表明,未掺杂ZnO及Zn_0.81Mg_0.19O薄膜为n型导电;而N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜呈p型导电。Zn_0.81Mg_0.19O和N-Al共掺杂Zn_0.81Mg_0.19O(p型)薄膜在维持ZnO纤锌矿结构的前提下,光学带隙随Mg掺杂量增加而增大。初步结果显示,优化工艺参数下通过Mg掺杂制备光学带隙可调的p型Zn_0.81Mg_0.19O薄膜,对于试制Zn_1-xMg_xO基同质p-n结、短波长(紫外、深紫外)器件等方面有重要意义。     

射频辅助N掺杂ZnO薄膜的生长及其光电特性

在MOCVD设备中采用改进的射频辅助生长装置,通过裂解N2及N-Al共掺杂的方法进行ZnO的p型掺杂研究。通过二次离子质谱(SIMS)、X射线衍射(XRD)、原子力显微镜(AFM)、光致发光(PL)谱等方法分析了薄膜中N杂质的浓度,以及射频功率与晶体质量、表面形貌以及光学特性之间的关系,并与Al掺杂和N掺杂的ZnO薄膜进行对比。实验结果表明,N掺杂的浓度高达1020cm-3;N-Al共掺杂极大地增加了ZnO的成核速率,其主要原因是N离化所起的作用;N-Al共掺的ZnO薄膜显示出p型性质,而N掺杂的ZnO薄膜由于N原子处于非激活状态而呈现高阻,这说明N-Al共掺杂对ZnO中N原子的活化起到一定作用。     

硼对氮掺杂的p型ZnO薄膜的影响

利用分子束外延设备在蓝宝石衬底上生长了B/N共掺的p型ZnO薄膜,对比了B/N共掺和N单掺杂样品的物理学性能。通过X射线光电子能谱测试证明了在薄膜中存在有B和B-N键。B/N共掺样品的空穴浓度比单一N掺杂样品高近两个量级。且ZnO：（B,N）薄膜在两年多的时间内一直显示稳定的p型电导。这是由于B-N键的存在提高了N在ZnO薄膜中的固溶度,且B-N键之间强的键能和B占据Zn位所表现的弱施主特性不会带来强的施主补偿效应,说明B是N掺杂ZnO薄膜的一种良好的共掺元素。     

Eu掺杂SiO2纳米基质的发光特性

采用溶胶-凝胶(sol-gel)法制备了Eu掺杂的SiO₂干凝胶,分别用光致发光(PL)光谱、透射电镜(TEM)、扫描电镜(SEM)、红外吸收(IR)谱等分析手段对样品进行了表征,研究了SiO₂的基质中Eu³⁺、Eu²⁺的发光特性以及退火温度对发射光谱的影响,并对其发光机理进行了分析。结果表明,样品掺杂均匀,颗粒尺寸大约在50~80 nm,硼(B)离子进入SiO₂网格,成为了基质的一部分,改变了基质的网络结构。当采用258 nm激发样品时,随着退火温度的升高,红光发射强度先增强后减弱。对于经800 ℃退火处理的样品红光发射最强,出现了576 nm(⁵D₀ →⁷F₀),620 nm(⁵D₀ →⁷F₂),658 nm(⁵D₀ →⁷F₃)3条谱线,其中主峰位于 620 nm红光发射,对应于Eu³⁺离子的⁵D₀ →⁷F₂超灵敏跃迁,进一步说明B离子参与到基质中,形成了Si—O—B键,导致Eu³⁺离子所处配位环境的对称性降低,从而有利于Eu³⁺离子的特征发射;当采用271 nm激发样品时,随着退火温度的升高,蓝光发射强度先增强后减弱,经850 ℃退火的样品400~500 nm蓝光发射最强,归属于Eu²⁺的5d→4f的跃迁发射,证明在铝离子(Al³⁺)存在的情形下,在高温退火过程中Al³⁺部分取代Si⁴⁺形成AlO^-₄基团,掺杂Eu³⁺填补AlO^-₄基团附近的空位,增加了Eu³⁺周围的AlO^-₄四面体中氧原子的电子给予能力,使得Eu³⁺还原成Eu²⁺,从而得到了较强的蓝光发射。但是,当退火温度达到900 ℃时,由于稀土离子发生位置的迁移形成团簇红光和蓝光都明显地降低。     

原子吸收光谱法间接研究组氨酸锌的配合反应

编程计算了不同pH条件下的组氨酸和锌离子的各种存在形式并分析了拟合分布图,研究了在硫化锌法原子吸收间接测定组氨酸时的pH值对原子吸收响应的影响及络合反应的机理。指出在pH 9.5左右最佳测定条件下,所形成的可溶性组氨酸锌配合物是由电中性的组氨酸基His+- 和带负一价电荷形态的组氨酸基His-与Zn(OH)₂共同形成的Zn(OH)₂·(C₆N₃O₂H₉)₂,Zn(OH)₂·[(C₆N₃O₂H₈)-]₂,Zn(OH)2·(C₆N₃O₂H₉)·[(C₆N₃O₂H₈)-]。结果表明,理论计算分析的结果与实验数据基本吻合,确定了硫化锌法原子吸收间接测定组氨酸时的配合物反应机理及配合物的组成结构。     

带隙可调的Al，Mg掺杂ZnO薄膜的制备

利用射频磁控溅射（RF-MS）方法,固定Al₂O₃掺杂量2 wt%,Mg掺杂量分别为1 wt%,3 wt%和5 wt%,在玻璃基底上制备了Al掺杂和Al,Mg共掺杂的ZnO薄膜,在500 ℃空气中退火2 h后,测量并比较了它们的光学和电学性质．结果表明,Al,Mg共掺杂的ZnO薄膜结晶质量良好,具有ZnO纤锌矿结构,具有较强的（002）面衍射峰,表明薄膜晶体沿c轴优先生长;与Al掺杂ZnO薄膜相比蓝端光透射率增加,1 wt%和3 wt% Mg掺杂薄 关键词： 射频磁控溅射 ZnO薄膜 Al Mg共掺杂     

Al和Sb共掺对ZnO有序阵列薄膜的结构和光学性能的影响

采用水热合成法在预先生长的ZnO种子层的玻璃衬底上制备出Al和Sb共掺ZnO纳米棒有序阵列薄膜. 通过X射线衍射、扫描电镜、透射电镜和选区电子衍射分析表明:所制备的薄膜由垂直于ZnO种子层的纳米棒组成, 呈单晶六角纤锌矿ZnO结构, 且沿[001]方向择优生长, 纳米棒的平均直径和长度分别为27.8 nm和1.02 μm. Al和Sb共掺ZnO纳米棒有序阵列薄膜的拉曼散射分析表明:相对于未掺杂ZnO薄膜的拉曼振动峰(580 cm^-1), Al和Sb共掺ZnO阵列薄膜的E₁(LO)振动模式存在拉曼位移. 当Al和Sb的掺杂量为3.0at%,4.0at%,5.0at%,6.0at%时, Al和Sb共掺ZnO阵列薄膜的拉曼振动峰的位移量分别为3,10,14,12 cm^-1. E₁ (LO) 振动模式位移是由Al和Sb掺杂ZnO产生的缺陷引起的. 室温光致发光结果表明:掺杂Al和Sb后, ZnO薄膜在545 nm处的发光强度减小,在414 nm处的发光强度增加. 这是由于掺杂Al和Sb后, ZnO薄膜中Zn_i缺陷增加, O_i缺陷减少引起的. 关键词： Al和Sb共掺ZnO薄膜 纳米棒有序阵列 结构表征 拉曼散射     

射频反应磁控溅射法退火生长Na-N共掺杂p-ZnO薄膜

采用射频反应磁控溅射法退火生长得到了Na-N共掺杂p-ZnO薄膜。XRD测试结果表明,退火前后均得到c轴择优取向的ZnO薄膜。Hall测试结果表明:退火后薄膜的电学性能明显改善,得到了p-ZnO薄膜,退火温度为450℃时取得最佳电学性能:室温电阻率为139.2Ω.cm,迁移率为0.2cm2.V-1.s-1,空穴浓度为2.5×1017cm-3。XPS分析表明:Na掺入ZnO中作为受主NaZn而存在,N主要以N—H键的形式存在,其受主NO的作用不明显,但是否存在NaZn-NO受主复合体,还需进一步的研究。     

p-Type conduction in phosphorus-doped ZnO thin films by MOCVD and thermal activation of the dopant

Phosphorus-doped p-type ZnO thin films have been realized by metalorganic chemical vapor deposition (MOCVD). The conduction type of ZnO films is greatly dependent on the growth temperature. ZnO films have the lowest resistivity of 11.3 Ωcm and the highest hole concentration of 8.84 × 10¹⁸ cm⁻³ at 420 °C. When the growth temperature is higher than 440 °C, p-type ZnO films cannot be achieved. All the films exhibited p-type conduction after annealing, and the electrical properties were improved comparing with the as-grown samples. Secondary ion mass spectroscopy (SIMS) test proved that phosphorus (P) has been incorporated into ZnO.     

Induction of p-type conduction in sputtered deposited Al-N codoped ZnO thin films

Al and N codoped ZnO thin films were grown on n-Si (100) substrate by sputtering technique. Hall effect measurements of as-grown films exhibited n-type conduction, however 500 °C Ar annealed codoped films showed p-type conductivity with a hole concentration of 9.9 × 10¹⁶ cm^− 3, resistivity of 15.95 Ω-cm and hole mobility of 3.95 cm²/Vs, respectively. Codoped ZnO thin films were found to be highly c-axis oriented with good crystal quality. A neutral acceptor-bound exciton and donor-acceptor-pair emissions that appeared at room temperature photoluminescence measurement verify p-type conduction in Al and N codoped ZnO film. The current-voltage characteristics of p-n heterojunction evidently showed a diode like rectifying behaviour.     

常压化学气相沉积技术生长ZnO∶H薄膜的光学性质

采用常压金属有机物化学气相沉积技术(APMOCVD),以二乙基锌(DEZn)为Zn源,去离子水(H2O)为氧源,N2作载气,在外延ZnO薄膜的反应气氛中通入少量氢气,在cAl2O3衬底上生长出了ZnO∶H薄膜。用X射线双晶衍射和光致发光谱对ZnO∶H薄膜的结晶性能和光学性质进行表征。结果表明,ZnO∶H薄膜(002)和(102)面的Ω扫描半峰全宽分别为46.1 mrad和81.4 mrad,表明该薄膜具有良好的结晶性能；室温下,ZnO∶H薄膜具有较强的紫外光发射(380 nm),在低温10 K光致发光谱中观测到位于3.3630 eV处与氢相关的中性施主束缚激子峰(I4)及其位于3.331 eV处的双电子卫星峰(TES)。采用退火的方法,通过观测I4峰的强度变化,研究了氢在ZnO∶H薄膜中的热稳定性。发现随着退火温度的升高,I4峰的强度逐渐减弱,表明在高温下退火,氢会从ZnO薄膜中逸出。     

Conversion of p-type to n-type conductivity in undoped ZnO films by increasing operating temperature

ZnO thin films with the thickness of about 15 nm on (0 0 0 1) sapphire substrates were prepared by pulsed laser deposition. X-ray photoelectron spectroscopy indicated that both as-grown and post-annealed ZnO thin films were oxygen-rich. H₂ sensing measurements of the films indicated that the conductivity type of both the unannealed and annealed ZnO films converted from p-type to n-type in process of increasing the operating temperature. However, the two films showed different conversion temperatures. The origin of the p-type conductivity in the unannealed and annealed ZnO films should be attributed to oxygen related defects and zinc vacancies related defects, respectively. The conversion of the conductivity type was due to the annealing out of the correlated defects. Moreover, p-type ZnO films can work at lower temperature than n-type ZnO films without obvious sensitivity loss.     

p-type ZnO thin films grown by RF plasma beam assisted Pulsed Laser Deposition

The high exciton binding energy and band gap energy of ZnO thin films open the prospect of fabricating semiconductor lasers in the ultraviolet spectral range. A prerequisite for laser diode fabrication is highly p-doped ZnO which was not reproducibly obtained up to now. Without intentional doping ZnO exhibits n-type conduction. ZnO thin films have been obtained by radio-frequency assisted pulsed laser deposition. A metallic Zn target was used for ablation in an oxygen and nitrogen RF discharge. The electrical and morphological properties of the films grown on Si were studied by Atomic Force Microscopy (AFM), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), optical absorption and Hall Effect measurements for different ratios between the nitrogen and oxygen content. The AFM images of the as-grown ZnO films reveal high quality surfaces with low values for the surface roughness and a sharp distribution of grains sizes as an effect of the RF discharge. The XRD patterns for all samples exhibit only (002) and (004) peaks indicating that the c-axis is always oriented normal to the substrate surface. The films present p-type conductivity with different carrier concentration and mobility depending on the nitrogen/oxygen ratio.     

Van der Pauw Hall Measurement on Intended Doped ZnO Films for p-Type Conductivity

A Van der Pauw Hall measurement is performed on the intended doped ZnO films （Na doped ZnO） grown by using the molecular beam epitaxial method. All as-grown samples show n-type conductivity, whereas the annealed samples （annealing temperature 900℃） show ambiguous carrier conductivity type （n- and p-type） in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li doped ZnO and in as-doped ZnO films by other groups before. However, by tracing the Hall voltage in the Van der Pauw Hall measurement, it is found that this alternative appearance of both n- and p-type conductivity is not intrinsic behavior of the intended doped ZnO films, but is due to the persistent photoconductivity effect in ZnO. The persistent photoconductivity effect would strongly affect the accurate determination of the carrier conductivity type of a highly resistive intended doped ZnO sample.     

在不同衬底上制备的ZnO薄膜透射率的研究

采用反应磁控溅射在不同结构衬底上生长ZnO薄膜,通过X-ray衍射(XRD)及透射光谱来分析薄膜的成膜情况,并得出在Al₂O₃/AlN复合基上溅射沉积的ZnO薄膜比单独在AlN薄膜衬底的结晶质量好且透过率也较高。而经不同的快速热退火温度验证,发现在400 ℃时,ZnO薄膜的结晶化及在(002)方向上的择优取向达到最好,并在可见光范围内的平均透过率达到88%以上。当退火温度超过450 ℃时,温度过高改变了ZnO薄膜的内部结构,使其氧原子和锌原子发生了较大距离的位移,导致薄膜内部缺陷的增多,从而存在过多的晶界,增加了其薄膜的散射机制,使光的透过性变差,退火温度为500 ℃时,薄膜的平均透过率为80%。