Showing papers on "Antimonide published in 1992"

Strained interband resonant tunneling negative resistance diode

Abstract: A double barrier tunnel diode (10) has a quantum well (12), a pair of electron injection layers (16) on either side of the quantum well (12), and a barrier layer (14) between each of the electron injection layers (16) and the quantum well (12), in a strained biaxial epitaxial relationship with the quantum well (12). The material of the quantum well (12) is chosen such that the biaxial strain is sufficient to reduce the energy of heavy holes in the quantum well (12) to less than the energy of the conduction band minimum energy of the electron injection layers (16). Preferably the quantum well (12) is made of gallium antimonide with from about 1 to about 40 atomic percent arsenic alloyed therein, the electron injection layers (16) are made of indium arsenide, and the barrier layers (14) are made of aluminum antimonide.

Negative electron affinity silicon heterojunction photocathodes with alkali antimonide intermediate layers

Abstract: In this paper, some new types of p‐Si(100) photocathodes with n‐K3Sb, n‐Na3Sb, and p‐Cs3Sb intermediate layers are fabricated. They are the (Si‐K3Sb‐Cs)‐O‐Cs and (Si‐Na3Sb‐Cs)‐O‐Cs negative electron affinity heterojunction photocathodes, and the (Si‐Cs3Sb‐Cs)‐O‐Cs positive electron affinity photocathode. For cathodes with n‐K3Sb, n‐Na3Sb, and p‐Cs3Sb intermediate layers, the maximum photoemission sensitivities attainable are, respectively, 1050, 950, and 150 μA/lm, and the measured minimum work functions of these cathodes are, respectively, 0.9, 1.0, and 0.85 eV. The photoemission stability of the Si photocathode with an alkali antimonide intermediate layer is better than that of the conventional Si‐O‐Cs and GaAs‐O‐Cs cathodes. The stability of the cathode is also related to the states of the cesium and oxygen during the activation process and the light illumination condition.

Selenium residual doping of (AlGa)Sb/GaSb epilayers grown by molecular beam epitaxy

Abstract: Some (AlGa)Sb layers grown by molecular beam epitaxy were found unexpectedly to be n type. Characterizing these layers by secondary ion mass spectrometry it was observed that they contained selenium (Se). Systematic analyses showed that selenium was present in all our antimonide layers, even those which were p type, at concentrations between 6×1014 and 3×1017 cm−3. The thermodynamical study of this contaminant incorporation led us to conclude that it comes from the solid antimony used for growths. That was confirmed by spark source mass spectrometry investigations. During growths, selenium behaves as other elements of group VI, sulphur for example, and this behavior is described by a simple kinetic model. It incorporates more easily at low substrate temperatures and saturates at levels depending on the antimony(Sb4) flux. At higher substrate temperatures, the incorporation is balanced by desorption according to an activation energy of 3.2 eV. As a consequence, selenium constitutes an accurate thermal probe to follow substrate temperature variations during growths. As could be expected, sulphur was also found to contaminate (AlGa)Sb films at levels of the order of a few 1015 cm−3. However, oxygen was not detected, probably being lower than 1016 cm−3 the detection limit of the analytical technique. This residual doping of antimonides by chalcogens presumably compensates their natural p‐type doping, but relationships with mobilities have not been evidenced yet.