The scanning tunneling microscopy and spectroscopy of GaSb_(1-x)Bi_(x) films of a few-nanometer thickness grown by molecular beam epitaxy

The ultrahigh vacuum scanning tunneling microscope(STM)was used to characterize the GaSb_(1-x)Bi_(x) films of a few nanometers thickness grown by the molecular beam epitaxy(MBE)on the GaSb buffer layer of 100 nm with the GaSb(100)substrates.The thickness of the GaSb_(1-x)Bi_(x) layers of the samples are 5 and 10 nm,respectively.For comparison,the GaSb buffer was also characterized and its STM image displays terraces whose surfaces are basically atomically flat and their roughness is generally less than 1 monolayer(ML).The surface of 5 nm GaSb_(1-x)Bi_(x) film reserves the same terraced morphology as the buffer layer.In contrast,the morphology of the 10 nm GaSb_(1-x)Bi_(x) film changes to the mound-like island structures with a height of a few MLs.The result implies the growth mode transition from the two-dimensional mode as displayed by the 5 nm film to the Stranski-Krastinov mode as displayed by the 10 nm film.The statistical analysis with the scanning tunneling spectroscopy(STS)measurements indicates that both the incorporation and the inhomogeneity of Bi atoms increase with the thickness of the GaSb_(1-x)Bi_(x) layer.

Nutritional quality of different potassium efficiency types of vegetable soybean as affected by potassium nutrition

Pot experiments were conducted in 2017,2019,and 2020 to examine the effects of potassium nutrition on the nutritional components of vege-table soybeans with different K efficiency at immature and mature stages.Two vegetable soybean varieties with higher K efficiency and two varieties with lower K efficiency were studied in the low available K soil under the conditions of no K and normal K fertilization.The results indicated that almost all nutritional components in vegetable soybean were affected by K,genotypes,interannual differences,and their inter-actions.In general,no K fertilization increased protein and amino acid concentrations but decreased oil,soluble sugar,sucrose,K,Mg,and Fe concentrations in immature and mature vegetable soybean.The sensitivity of nutritional components to K nutrition differed among varieties.For instance,K high-efficiency varieties generally exhibited higher protein and amino acid concentrations without K application.K high-efficiency vegetable soybeans are low-K tolerance varieties to isoflavones.The results of this study provide insights for high yield and quality vegetable soybean breeding against soil K deficiency.