MOCVD Epitaxial Growth Of In(GaSb) Thin Films And The Quantum Dots

Antimonide is an important part of III-V semiconductor material system.Because of unique energy band structure,small effective mass and high electron mobility,it has great potential in ultra-high speed and low power devices and infrared photoelectric field.Especially,the introduction of low dimensional structure such as quantum dot and superlattice and the introduction of type II band structure make the wavelength extend from near mid infrared to far infrared.Antimony device is considered to be the important development direction of the third generation infrared technology.However,because of the low saturated vapor pressure of organic antimony source,high quality antimony materials is difficult to be grown by MOCVD technology,which severely limits the large-scale commercial production of high performance devices.Based on MOCVD technology,the growth and characteristics of InGaSb film and InGaSb and GaSb quantum dots are studied in this paper.1.The InGaSb films were grown on GaSb substrates by MOCVD technology.The effects of growth temperature,V/III and Ga/III on the properties of InGaSb films were studied.When the temperature increased from 430°C to 510°C,the surface morphology and crystalline quality of InGaSb films were greatly improved.Considering the incorporation of In atoms,470°C is the best growth temperature,and the experimental phenomena are explained by the thermodynamic.When the ratio of V/III increases from0.5 to 2,the surface roughness of InGaSb film decreases obviously.The crystallization quality is the best when V/III is 1.5,and the full width of half maximum?FWHM?of XRD rocking curve is 0.47 degree.When Ga/III increased from 0.3 to 0.8,the surface morphology and crystalline quality of InGaSb films were greatly improved,and explained from bond strength and kinetics.2.InGaSb quantum dots were prepared on GaAs substrates by MOCVD technology.The growth parameters such as growth temperature,reaction chamber pressure,growth time and interruption time were studied,and the effects of deposition thickness and GaSb buffer layer on the morphology of InGaSb quantum dots were also studied.The temperature of 500°C,pressure of 100mbar,growth time of 5s,growth interruption time of 10s,quantum dots have the maximum density and elongated along[110]direction,the density is 5.5×10⁹cm^-2,the average height of 11nm,the average diameter of 72 nm,average aspect ratio of about 1.5.3.GaSb quantum dots were prepared on GaAs substrates by MOCVD technology.By the Sb surface treatment,a floating layer of Sb-Sb with low surface energy is formed on a GaAs substrate to achieve growth of GaSb quantum dots with an interfical misfit?IMF?growth mode.The quantum dots elongated along[110]direction.At the temperature of 500°C,pressure of 40mbar,growth time of 20s,quantum dots have density of 1.2×10¹⁰cm^-2,the average diameter of 43nm,the average height of 5.8nm.The effect of growth parameters and droplet epitaxial growth mode on the morphology of GaSb quantum dots were studied.Quantum dots have density of 10⁹cm^-2,the average diameter of 43nm,the average height of 5.8nm grown by droplet epitaxy technology.4.The effects of source input flow and reactor chamber pressure on the anisotropy of GaSb quantum dots and the effect of Sb protection on the growth mechanism and morphology of quantum dots were investigated.The high input flux of organic source and low reaction chamber pressure,the anisotropy of the quantum dot morphology can be suppressed.Although the high source input flow rate can better suppress the anisotropy,it leads to larger size.Moreover,it is difficult to control the distribution uniformity of the quantum dots during the short growth time?<5s?.The use of low pressure of 40mbar can not only effectively suppress the anisotropy of the quantum dots,but also the size of the quantum dots can be adjusted in a larger range by the growth time.The treatment of Sb protection before growth is similar to the effect of Sb surface treatment,which promotes the formation of IMF growth mode.