有機金屬化學氣相沉積成長ZnGa_2O_4薄膜及其特性探討

Characterization of ZnGa_2O_4 Thin Films Grown by MOCVD

黃瓊儀(Chiung-Yi Huang) ； 歐信良(Sin-Liang Ou) ； 洪瑞華(Ray-Hua Horng)

《真空科技》 31卷1期 (2018/03) Pp. 20~1-20~6

摘要

本研究是利用有機金屬化學氣相沉積方法成長ZnGa_2O_4薄膜，並探討其材料特性，包括晶相結構、電性質、發光特性與鍵結特性等。在薄膜成長過程中，TEGa及O_2的流量分別為50與200 sccm，而DEZn的流量則是由10增加到60 sccm；基板溫度與成長時間分別為670°C及90分鐘。由X光繞射分析得知，當DEZn流量為10 sccm時，薄膜是呈現(-201)優選方向的β-Ga_2O_3單晶相。當DEZn的流量增加時(30-60 sccm)，薄膜結構逐漸轉變成具(111)優選方向的ZnGa_2O_4單晶相。此外，我們也使用霍爾量測分析薄膜的電性質。利用DEZn流量為10 sccm所鍍製的薄膜，其電特性是相對較差的。當DEZn流量從30增加到60 sccm，薄膜載子濃度可從1.94×10^(14)提升到6.72×10^(16)cm^(-3)，電阻率則是從5730逐漸降低至68 Ω-cm。結果顯示ZnGa_2O_4在DEZn流量為50-60 sccm時，具有較佳的電性質。

關鍵字

ZnGa_2O_4 ； 有機金屬化學氣相沉積 ； 單晶結構 ； 電特性

並列摘要

In this study, the ZnGa_2O_4 thin films were prepared by metalorganic chemical vapor deposition (MOCVD) at a substrate temperature of 670 °C for 90 min. During the film growth, the flow rates of TEGa and O_2 were fixed at 50 and 200 sccm, respectively. Meanwhile, the flow rate of DEZn was varied from 10 to 60 sccm. The influence of DEZn flow rate on the structural, electrical, optical, cathodoluminescence, and bonding characteristics of ZnGa_2O_4 films were investigated in detail. Based on the results of X-ray diffraction (XRD) measurements, the crystal structure of the film prepared at a DEZn flow rate of 10 sccm was indexed to (-201) β-oriented Ga_2O_3 single crystalline phase. However, when the flow rate of DEZn was increased, we can observe that the XRD peaks of these films all gradually shifted to low angle position. According to our analyses, with increasing the flow rate of DEZn to 30-60 sccm, these films all possess the ZnGa_2O_4 single crystalline phase with the (111) preferred orientation. Additionally, the Hall measurement was used to characterize the electrical properties of these films, such as carrier concentration, mobility, and resistivity. As the film was deposited at a DEZn flow rate of 10 sccm, its electrical characteristics was much worse than those of the other films, resulting from the intrinsic behavior of β-Ga_2O_3 material. Further increasing the DEZn flow rate from 30 to 60 sccm, the carrier concentration of the film increased from 1.94×10^(14) to 6.72×10^(16) cm^(-3). Besides, the resistivity of the film can be decreased from 5730 to 68 Ω-cm. The electrical properties present the ZnGa_2O_4 films grown at the DEZn flow rate of 50-60 sccm have the better electrical properties than those of the others, indicating these films are more feasible for optoelectronic applications.

並列關鍵字

ZnGa_2O_4 ； MOCVD ； single crystalline structure ； electrical properties