脉冲激光delta-掺杂 III-V 族 AlNx（x=3，4）团簇制备高空穴浓度p-型氧化锌的研究

ZnO has been paid much more attention because of its potential application in the ultraviolet light emitting diodes (UV-LEDs)and lasers. However, the problem associated with the preparation of stable P-type ZnO with high hole density hinders the device application of UV-LEDs. Although substantial studies have been focused on this challenge,there are, so far, no efficient and practical doping methods to prepare stable p-ZnO with high hole density. In this study, we introduce a new approach to prepare p-type ZnO and BeMgZnO with dopings of (Al,N) III-V cluster.The chemical bonds of N element with Al is much stronger than the Zn-N bond. The Al-containing clusters will capture and stabilize the N atoms in ZnO. First-principles calculations demonstrated that GaNx (x=3,4)clusters are formed preferentially in the growth of ZnO under the N-rich ambience. Comparing to the N atom alone doped into ZnO, the enthalpy of cluster formation decreases.The local bonding enviroment around the dopants enhances and maximizes the stability and solubility of substutional N in ZnO. Very recently, a spin-polarized density-functional theory reveals a single hole state,created by (Ga,N) cluster doping in ZnO,contains the contribution from each of the N atoms in the cluster.The hole from a cluster has enhanced delocalization nature. To realize the p-ZnO with cluster doping experimentally, we employ new doping technique of pulsed laser delta-doping clusters of AlNx in MBE growth of ZnO thin films. The main advantage of this method is that chemical bonds of acceptors have been formed before being incorporated into ZnO. With N-rich circumstance, the excimer laser pulses bombard the AlN target and generate the (Al,N)-clusters. And then they will be directly doped into ZnO. In this proposal, we also explore the (Al,N) cluster doping in BeMgZnO. BeO has a wurtzite structure. Introducing Be element can suppress the phase separation in the MgZnO growth and reduce the lattice mismatch between MgZnO and ZnO. This can improve the structural quality of ZnO-based devices. In summary, we will try to make a breakthrough in the fabrication of p-ZnO with the introduction of new doping methods. A cluster doping, achieving p-type ZnO and BeMgZnO with high hole density,will be investigated systematically.We hope to push forward to advance the ZnO-based research and finally realize ZnO-based light emitter with good performance.

高空穴浓度,电学性能稳定的p-ZnO是限制其紫外发光器件应用化的瓶颈。针对此问题，我们提出分子束外延技术中引入脉冲激光掺杂AlNx团簇的方法制备p-型ZnO和BeMgZnO的研究方案。理论表明，与单独掺氮相比，GaNx（x=3-4）团簇掺杂可以降低受主形成能，并能减小空穴的离化能。本研究中，我们引入AlNx是出于如下考虑: Al-N和Al-O键比Ga-N，Ga-O键更稳定，因而可以把氮更有效的固定在氧化锌中, 形成稳定的p-型氧化锌。 我们目前氧化Zn3N2：Al制备p-ZnO和对其退火的实验证明了这种p-ZnO的热稳定性显著增强。为了进一步增加空穴浓度和结晶质量，在富氮的气氛下，利用高能激光脉冲轰击AlN靶材产生团簇，采用delta-掺杂的方式，控制外延膜表面反应，在ZnO中形成团簇。预期能够得到性能稳定，高空穴浓度的p-型氧化锌,进而完善ZnO p/n结器件结构,提高电注入发光效率。

本项目系统研究了本征氧化锌的缺陷性质；p-型氧化锌的制备和特性；超高质量宽带隙氧化物微米线及其自驱动高灵敏度日盲探测器件。利用分子束外延技术，通过引入氧化镁过渡层，得到了近化学配比的氧化锌单晶薄膜，氧气气氛下退火实验表明，低于500度时，减少一些缺陷密度；当高于500度时，即使在氧气氛下，氧空位也会产生。这表明如何提供氧化锌的热稳定性，是将来提高器件的关键。在氧化锌的p-型掺杂工作中，我们利用热氧化掺铝氮化锌的反向掺杂的方法，获得了热稳定性明显提高的p-型氧化锌：在800oC，900oC下退火，仍为p-型。在此基础上，通过引入氧化锌陶瓷靶，氮化铝陶瓷靶共溅射的方法，进一步提高了氧化锌薄膜的结晶质量，得到了空穴载流子浓度为1.58x1017cm-3的p-型氧化锌。其电学特性随时间的变化也表明其稳定性良好。通过拓展反向掺杂方法，得到了氮氧锌，氮氧镓等合金，其能带可以在1.3-3.2 eV和2.0-5.0 eV连续调节，这将拓展这类光电材料的应用波段。最后，利用化学汽相沉积的方法，得到了超长氧化锌，氧化镓单晶微米线。通过优化器件结构，得到光暗电流比达到1000的超高响应自驱动日盲探测器件。