【作者】 霍炳至；

【导师】 胡礼中；

【作者基本信息】 大连理工大学 ， 微电子学与固体电子学， 2009， 博士

【摘要】 ZnO是一种重要的宽带隙半导体氧化物材料。其较大的禁带宽度(3.37eV)和激子束缚能(60meV)以及较好的化学稳定性,使其成为制造光电子器件的理想材料。脉冲激光沉积系统是一种相对先进的薄膜生长设备,其优点之一是可以精确地把需要生长的材料的厚度误差控制在一个极小的范围。这使得脉冲激光沉积非常适合用于研究结构复杂的ZnO薄膜。本论文的研究工作主要着眼于利用脉冲激光沉积方法生长ZnO及其他相关多层膜材料,研究其生长条件、性能和在制备光电子器件中潜在的应用价值。论文的研究结果概括如下:1.在蓝宝石衬底上550℃、60Pa氧压的条件下生长出ZnO/ZnMgO超晶格。超晶格的光致发光谱的近带边发射峰的峰位在3.3-3.5eV的范围内可控。从强度归一化的低温光致发光谱中可以观察到激子束缚能随着光学声子伴随的自由激子峰的强度变大而减小。将超晶格生长在650℃、60Pa氧压条件下沉积的ZnO缓冲层上,可以提高其质量,且具有纳米针形貌,其PL光谱具有垂直于衬底向上的方向性,该方向性与激光角度没有关系。这对研究微谐振腔有一定的应用价值。2.在蓝宝石衬底上550℃、60Pa氧压的条件下生长出ZnO/MgO多层膜反射器。ZnO/MgO反射器是由交替生长九个周期的ZnO和MgO构成的。实验表明,通过改变生长时间,可以控制ZnO/MgO反射器的反射波长。3.在蓝宝石衬底上生长一层较薄的MgO或者ZnMgO缓冲层,通过改变缓冲层的厚度,就可以极大地改变生长在缓冲层上面的ZnO层的形貌,并且观察到了纳米ZnO结构。同时通过改变MgO缓冲层的厚度和ZnO的生长速度,得知ZnO纳米结构必须在极薄MgO缓冲层与较慢的ZnO生长速度条件下才能成功制备。用ZnMgO作为缓冲层生长出来的ZnO纳米柱方向凌乱,比较适合应用在太阳能电池领域。4.成功制备多孔MgO。在生长速度慢,生长温度高,设备的真空度高的条件下先生长一层极薄的ZnO缓冲层,然后再生长MgO,便可成功制备多孔MgO。孔洞本身由MgO构成,而孔洞的底部是ZnO。该多孔MgO的孔洞距离大,可以用来生长纳米颗粒组间距较大的材料。5.用PLD生长的AlN层可以在ZnO退火的时候防止其O原子的逃逸。因为ZnO薄膜中O原子的逃逸经常会产生O空位,使p型掺杂产生困难,这一结果对制备质量更高的p型ZnO及其光电器件有潜在的应用价值。在ZnO光致发光谱中位于3.336 eV的发射峰尚未被人们理解清楚,我们证明它与ZnO的点缺陷无关,并且推测此峰可能是由ZnO位错引起的。更多还原

【Abstract】 ZnO is an important wide gap material.Because of the wide band gap of 3.37 eV,large excition binding energy gap semiconductor of 60 meV,and high chemical stability,ZnO is an excellent candidate for the fabrication of nanoscale electronic and optoelectronic devices.The aim of this article is researching on ZnO and the related multilayers grown by pulsed laser deposition.The results are:1.The superlattices were directly grown by the pulsed laser deposition method.In low temperature PL,it can be observed that the coupling strength between excitons and longitudinal optical phonons is a decreasing function of wellwidth if the wellwidth is small. But if the superlattice was grown on the ZnO buffer layer,the buffer layer could not only increase the quality of superlattice,but also change the common morphology of the superlattice to the nanostructure morphology.Direction of the PL of superlattice is also almost perpendicular to the substrate and has nothing to do with the incident angle of the laser.This nanostructure would be useful for researching microcavity,or fabricating a 50-100 nm diameter beam of light with a strong orientation.2.ZnO/MgO multilayers samples were grown on sapphire(0001) substrate.The transmission and photoluminescence spectra show that the samples exhibit some Distribute Bragg Reflection phenomenon.3.ZnO films with different thickness MgO buffer layers have been grown on sapphire substrate.The SEM results show that the grain size in the direction parallel to the substrate surface increase with the MgO layer thickness.Thin MgO buffer layer and small growth rate of the ZnO layer are the key factors for depositing ZnO nanowires.The ZnO nanowires can be useful for frabricating solar cell.4.The MgO pores with thin ZnO layer at the bottom were also grown on sapphire.Thin ZnO layer on sapphire can form islands.When the substrate is sapphire,MgO is hard to be deposited on the ZnO small islands at high temperature and high vacuum.So this phenomenon can be used for fabricating the porous MgO.It is evident that porous material can be realized at high temperature and high vacuum by pulsed laser deposition method. Porous MgO can be used for fabricating the materials in which the shortest distance between the two nanoparticles is about 5 um. 5.The ZnO films coated with AlN layers were annealed.It can be observed from room temperature photoluminescence that the ZnO films coated with AlN layers do not show a deep level peak.Because the O atoms in ZnO surface would form oxygen and increase the concentration of oxygen vacancies,which is a donor defect in ZnO,by using the high temperature stability of AlN,the oxygen vacancies could be controlled for realizing the p-type ZnO.The peak at about 3.336 eV may be due to the dislocation.更多还原