RU2226306C2 - Quantum-beat based resonance-tuned semiconductor device - Google Patents

Abstract

FIELD: microelectronics, nanotechnology, and optoelectronics. SUBSTANCE: thin-film nanocrystal silicon doped with rhodium atoms until dopant-induced state is attained in forbidden gap of nanocrystal silicon with energies of 0.353 to 0.591 eV from bottom of silicon conductive region makes it possible to produce high-frequency oscillations of electrical or optical signals at frequency higher than 10¹³ Hz in electromagnetic field when voltage is applied. EFFECT: enhanced speed, facilitated manufacture. 1 cl, 4 dwg

Description

The invention relates to semiconductor devices and electronic devices with quantum potential wells.

A device [1] is known containing a layered structure of doped gallium arsenide (GaAs), unalloyed AlAs with a thickness of 5 nm, forming the first potential barrier, undoped GaAs with a thickness of 5 nm, representing an energy potential quantum well, then unalloyed AlAs with a thickness of 5 nm, which is the second potential barrier , and doped GaAs.

The principle of operation of a resonant tunneling device [1] is as follows. As the applied voltage to the outer layers of GaAs doped increases, the current flowing through the layers from the emitter to the collector initially increases nonlinearly to its resonance value, then decreases during detuning from resonance due to the existence of potential barriers, and then increases nonresonantly due to the appearance of a leakage current .

The disadvantage of this technical solution is the complexity of manufacturing super-thin layers, the high complexity of the molecular beam epitaxy of the layers and low speed compared to the frequencies of the optical range.

Closest to the claimed device is [2], which includes Al ₂ O ₃ layers forming potential barriers, source and drain electrodes, and wide (135 nm) and narrow (50 nm) gates that allow controlling the source-drain current. The generated energy potential well with a depth of 10-15 meV and a barrier height close to the Fermi electron energy allows the resonant tunneling process to be realized with a frequency from 90 to 360 GHz when applying a small voltage value.

The disadvantages of the prototype [2] are low speed compared to the frequencies of the optical range and sensitivity to temperature, which leads to the need to cool the device due to the increase in uncontrolled leakage current during heating. In addition, the disadvantage is the complexity of its manufacture, due to the formation of a potential energy well with specified parameters. The inventive device is aimed at increasing the speed of the system, reducing the complexity of its manufacture and increasing the stability of its characteristics with respect to temperature.

The solution of this problem is achieved by the fact that when forming the energy potential well, a silicon nanocrystal is used (Fig. 1), the potential barrier is formed by a layer of an amorphous hydrogenated SiO _x compound surrounding the nanocrystals, and the resonance levels in the band gap of silicon are realized due to impurity rhodium atoms (with a concentration 10 ¹⁴ cm ³ ) with energies of 0.353 and 0.591 eV from the bottom of the conduction band. The achievement of the claimed technical result is ensured by the fact that the effect of quantum interference of the levels of the rhodium atom with a ratio of cross sections for them of 0.04 is used. Optical or electric pumping of the conduction band due to the creation of nonequilibrium carriers leads to their relaxation to impurity levels of rhodium Rh1 and Rh2 with lifetimes of 0.19 and 4.6 ns, respectively [3].

Quantum level beats or quantum modulation of the photoluminescent signal of an irradiated semiconductor material is due to the effect of quantum interference of fluorescent signals from levels closely located on the energy diagram [4]. Moreover, the wave function of an excited electron is a linear combination of level probability functions

where a and b are the amplitudes of the probability of finding an electron at levels 1 and 2;

G ₁ and G ₂ are the spectral widths of the levels.

Then the radiation intensity or spectral characteristic of the current will have the form

where W ₁₂ = E ₁₂ / h, E ₁₂ is the difference in the energy positions of the two levels 1 and 2.

The drawing schematically shows a resonant tunneling semiconductor device (figure 2) based on quantum beat levels [5]. The device contains a metal electrode, a layer of polycrystalline silicon doped with rhodium, 300 nm thick, a p-type silicon substrate of conductivity and a second metal electrode. The applied voltage creates a current that depends non-linearly on the voltage. The created field strength of the order of 8 × 10 ⁵ V / m due to the voltage applied to the electrodes makes it possible to realize the resonant mode of operation of the device, in which tunneling or relaxation of electrons is carried out through the upper level Rh1 at a possible oscillation frequency of 10 ¹³ Hz.

The complexity is reduced due to the use of polycrystalline silicon doped with rhodium atoms, obtained as a result of vacuum-plasma deposition [5].

An increase in stability with respect to temperature is achieved by using fixed discrete levels of rhodium in the band gap of silicon to realize resonant tunneling.

Examples of specific performance may be as follows.

1. A polycrystalline silicon-based polar transistor consists of an electrode serving as a source, a polycrystalline silicon film, a gate electrode, and a drain electrode. The voltage applied to the gate regulates the type of non-linear dependence of the current-voltage characteristic (I-Vсi) of the device (see Fig. 3).

2. A photoelectronic device that converts light energy into electrical energy is made in the form of a thin film of polycrystalline silicon, on the surface of which two electrodes are deposited. Due to the irradiation of light with a specific wavelength, nonequilibrium carriers are generated that serve as a current source (see Fig. 4).

Sources of information

1. Maezawa K., NTT Review. V. 8, N 4, 1996, p. 48-51.

2. Hu Q. et al. Semiconductor Science and Technology. V. 11, 1996, p. 1888-1894.

3. Lisiak K. and Milnes A. Solid-State Electronics. V. 19, 1976, p. 115-119.

4. Milovzorov D. Electrochemical and Solid State Letters. V. 4, 2001, p. 1-3.

5. Milovzorov D., Inokuma T., Kurata Y. and Hasegawa S. Journal of Electrochemical Society. V. 145, N 10, 1998, p. 3615-3620.

Claims (1)

A device containing a semiconductor element and electrodes attached to it to create an electric field that creates a current, characterized in that the semiconductor element is made in the form of a film of polycrystalline silicon doped with rhodium atoms, creating levels in the band gap of silicon with energies of 0.353 and 0.591 eV from the bottom of the zone silicon conductivity, which allows resonant tunneling and quantum beats of the intensity of electrical and optical signals.

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