原子层沉积Al_(2)O_(3)钝化对InAs/InGaAsSbⅡ类超晶格发光特性的影响

Effect of Atomic Layer Deposition Al_(2)O_(3)Passivation on the Luminescence Properties of InAs/InGaAsSb Type-Ⅱ Superlattices

提出一种基于干法刻蚀与原子层沉积相结合的钝化方法,采用干法刻蚀去除InAs/InGaAsSb超晶格表面及端面固有的氧化层,利用原子层沉积Al_(2)O_(3)薄膜钝化刻蚀表面,对钝化前后光致发光光谱的表征研究其发光性能与长期稳定性。处理后超晶格的As 3d谱中As-O键相关的峰消失表明其表面的氧化物被有效去除。样品的发光强度与激发光功率之间的拟合系数α从1.17减小为1.02,表明激子主导的发光占比增加。连续五天的红外光谱测试发现,处理后样品发光强度降低为原来的89%,而未处理样品的发光强度降低为原来的76%,表明处理后超晶格表现出更好发光稳定性。本研究为提升InAs/InGaAsSb超晶格性能、促进其光电探测领域的应用提供参考。

As an emerging mid-infrared semiconductor material,InAs/InGaAsSb superlattice possesses a wide working range covering the infrared spectrum from 2~30μm,holding promising potential for applications in fields of infrared imaging.Compared to traditional InAs/GaSb superlattices,InAs/InGaAsSb superlattice has the advantages of high electronic effective mass,low Auger recombination efficiency,and long carrier lifetimes,making it a potential material for designing third-generation infrared photodetectors.Hence,the study on InAs/InGaAsSb superlattice has become the current research hotspot.However,the surfaces and cross-sections of InAs/InGaAsSb superlattices are easily oxidated in air,resulting in the formation of gallium oxide and arsenious oxide.These oxides act as non-radiative recombination centers,reducing minority carrier lifetimes and severely limiting the performance improvement of infrared photodetectors.Therefore,it is of great significance for surface treatment to remove surface oxides and reduce surface state density in InAs/InGaAsSb superlattice materials.Recently,research on the passivation of InAs/InGaAsSb superlattices focuses solely on surface treatment.However,the cross-sections,consisting of distinct InAs and InGaAsSb structures,respectively,exhibit heightened susceptibility to being oxidated.Consequently,it is necessary to remove the inherent oxide layers from the cross-section by etching and passivate the surfaces to prevent further oxidation.Accordingly,this paper proposes a passivation technique integrating dry etching and atomic layer deposition.Dry etching is employed to remove the inherent oxide layers from the surface and cross-section of InAs/InGaAsSb superlattices,followed by the deposition of an Al_(2)O_(3)thin film through atomic layer deposition to passivate the etched surfaces.This approach aims to enhance the emission performance and long-term optical stability of InAs/InGaAsSb superlattices.In order to characterize the crystal quality of the InAs/InGaAsSb superlattice,the double-crystal Xray diffraction(XRD)is employed.It is easy to find six orders of satellite peaks in XRD patterns,indicating excellent crystal and interface quality between InAs layers and InGaAsSb layers.Additionally,a tiny difference between the 0th-order diffraction peak and the substrate peak is observed,which is attributed to internal strain-induced effects.The surface roughness before and after treatment is analyzed by using atomic force microscopy,showing a significant reduction in surface roughness from 6.32Åfor untreated samples to 1.93Åfor the treated superlattice material.To verify the successful elimination of surface and cross-section oxides,X-ray Photoelectron Spectroscopy(XPS)is employed on the superlattice before and after treatment.For the As 3d spectrum of the untreated superlattice,the peak related to the As-O bond is observed in addition to the As 3d1/2 and As 3d3/2 peaks.However,this peak associated with the As-O bond disappears in the spectrum of the surface-treated superlattice,indicating complete removal of the surface oxide layer.The Photoluminescence(PL)characteristics of the superlattice are measured before and after treatment.The PL spectra reveal an increase in emission intensity and a decrease in full width at half maximum after passivation,which is attributed to the effective reduction of non-radiative recombination through the removal of surface oxides.Continuous PL measurement over five days showed that the emission intensity of the treated samples decreased to 89%of the original intensity,while the emission intensity of untreated samples decreased to 76%of the original intensity.These results indicate better emission stability of the superlattice after treatment.The power-dependent and temperature-dependent PL spectra are employed to analyze the mechanism of the increase in emission intensity and the improvement in emission stability.The relationship between PL intensity and excitation power is analyzed to verify the origin of the emission.The fitting coefficientαdecreased from 1.17 to 1.02 after treatment,indicating an increased proportion of exciton-dominated emission.The Arrhenius formula is used to fit the relationship between emission intensity and measurement temperature,revealing that the activation energy E1 increased by 5.13~13.73 meV and E2 increased by 121.92~130.04 meV for the treated samples compared to untreated samples,which indicates a significant suppression of non-radiative recombination,especially at high temperatures.This work lays the foundation for enhancing the performance of InAs/InGaAsSb superlattices and promoting their applications in the field of optoelectronic detection.