光谱分析气体状态对近空间升华沉积CdTe多晶薄膜的影响

Spectral Analyzing Effects of Atmosphere States on the Structure and Characteristics of CdTe Polycrystalline Thin Films Made by Close-Spaced Sublimation

在CdTe多晶薄膜太阳电池制备中用近空间升华法生长了CdTe多晶薄膜, 沉积工作气体的状态决定了薄膜的结构、性质. 文章首先分析了近空间沉积的物理机制, 测量了近空间沉积装置内的温度分布, 使用氩氧混合气体为工作气体, 其中重点讨论了该气体状态(包括气氛和气压)与薄膜的初期成核的关系, 即择优取向程度和光能隙与气氛和气压的关系. 结果表明, (1)不同气氛下沉积的CdTe薄膜均为立方相结构. 随氧浓度的增加, σ增加, 氧浓度为6%时, σ最大, 之后随氧浓度增加, σ降低, 在12%达到最小, 然后随氧浓度的增加而增加, 在氧浓度为9%时沉积的结晶更完整. CdTe薄膜的光能隙为1.50～1.51 eV; (2)在氩氧气氛下氧浓度为9%, 不同气压下制备的样品, 均有立方相CdTe, 此外, 还有CdS和SnO2:F衍射峰. CdTe晶粒随气压增加有减小趋势, 随气压的增加, 透过率呈下降趋势, 相应的CdTe吸收边向短波方向移动; (3)在氩氧气氛下氧浓度为9%, 采用衬底温度550 ℃, 源温度620 ℃, 沉积时间4 min时制备的CdTe多晶薄膜获得了转换效率优良的结构为SnO2:F/CdS/CdTe/Au的集成电池.

The structure and characteristics of CclTe thin films are dependent on the working atmosphere states in close-spaced sublimation. In the present paper, CdTe polycrystalline thin films were deposited by CSS in mixture atmosphere of argon and oxygen. The physical mechanism of CSS was analyzed, and the temperature distribution in CSS system was measured. The dependence of preliminary nucleus creation on the atmosphere states （involving component and pressure） was studied. Transparencies were measured and optic energy gaps were calculated. The results show that：（1） The CdTe films deposited in different atmospheres are cubic structure. With increasing oxygen concentration, σ increases and reaches the maximum at 6% oxygen concentration, then reduces, and increases again after passing the point at 12% oxygen concentration. Among them, the sample depositing at 9% oxygen concentration is the best. The optic energy gaps are 1.50-1.51eV for all CdTe films. （2） The samples depositing at different pressures at 9% oxygen concentration are all cubical structure of CdTe, and the diffraction peaks of CdS and ShO2： F still appear. With the gas pressure increasing, the crystal size of CdTe minishes, the transparency of the thin film goes down, and the absorption side shifts to the short-wave direction. （3） The polycrystalline thin films with high quality deposit in 4 minutes under the depositing condition that the substrate temperature is 550℃, and source temperature is 620 ℃ at 9% oxygen concentration.