JPH0485886A - Semiconductor electrode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the structure of a semiconductor electrode body on which a compound semiconductor is mounted, for example.

[Prior art] Figure 3 shows 1, for example, a publication (optoelectronics, p. 75).
1 is a configuration diagram of a light-emitting diode (LED), which is a conventional semiconductor electrode body, shown in 1999, written by Tadashi Sueda, published by Shokodo.

In the figure, (11) is GaAs (semiconductor), (12) is p
-AIGaAs (p-type semiconductor), (13) is n-AIG
aAs (n-type semiconductor), (4) is a transparent electrode, (5) is a power source, the emission wavelength is from 660 nm to 880 nm, and through the ρ-type semiconductor (12) and the n-type semiconductor (13),
Carriers are injected into the semiconductor (11) using a power source (5) to cause it to emit light. LEDs have a wide range of applications in various electronic devices such as display devices and optical information processing devices.

[Problems to be Solved by the Invention] Although the development of blue LEDs has become active in recent years, their luminous efficiency and luminous intensity are insufficient for practical use. That is, the wavelength or energy of the light emitted from the LED is within the semiconductor's forbidden band width (E
, ). The wavelength λ of light is expressed by the following formula.

λ=hC,/E.

Here, h is a blank constant and C0 is the speed of light. Applications of blue LEDs are limited to those with an Eg of 2.6 eV or more. Currently, G is used as a semiconductor material that satisfies these requirements.
aN, SiC, ZnS, and Zn5e are being studied. However, stable methods for forming films of these materials have not been established, and methods for forming films of n-type semiconductors and p-type semiconductors, that is, methods for electrically connecting semiconductors, have not been established.
The carrier injection efficiency does not increase, and the luminous efficiency and luminous intensity are low.To solve these problems, it is possible to increase the driving voltage, but considering that the ED is especially applied to small electronic devices, it is difficult to actually use it. ).

This invention was made to solve this problem, and it increases the efficiency of carrier injection into the inside of a semiconductor film, and makes it possible to inject carriers with high efficiency into a semiconductor with a wide band gap, for example, an E9 of 2.6 eV or more. The object of the present invention is to obtain a semiconductor electrode body having a structure in which:

[Means for Solving the Problems] The semiconductor electrode body of the present invention includes a first semiconductor film made of two or more types of elements, this I! 1 n-type 1 provided on one side of the semiconductor film
! 2 semiconductor film and a P-type second semiconductor film provided on the other side of the j1111 semiconductor, the n-type (
or a p-type) semiconductor film, at least the back side of the first semiconductor is partially deficient in the constituent elements of the first semiconductor, and
It is characterized in that the carrier concentration gradually and monotonically changes from the semiconductor film to the n-type (or p-type) semiconductor film.

[Function] In the present invention, a part of the constituent elements of the first semiconductor film is missing from at least the first semiconductor film side of the n-type (or p-type) semiconductor film, and the n-type (or p-type) semiconductor film is removed from the first semiconductor film.
type) The carrier concentration gradually changes monotonically toward the semiconductor film. The electrical resistance value of the portion where this composition ratio changes continuously and the carrier concentration gradually monotonically changes from the first semiconductor film to the n-type (or p-type) semiconductor film is the electrical resistance of the first semiconductor film. In other words, it has a high carrier density. Therefore, the injection efficiency of carriers into the film is significantly increased compared to a conventional electrode body in which the composition ratio does not change continuously.

[Example] FIG. 1 is a configuration diagram of a semiconductor electrode body according to an example of the present invention. In this case, the first semiconductor film (1) is composed of two constituent elements X and Y whose stoichiometric composition ratios are a and a, respectively.
Compound semiconductor X −Y b, which is b.
2) is a P-type 113 semiconductor film, (3) is an n-type semiconductor film, (
4) is a transparent electrode, and (5) is a power source. In addition, (6) is X in which the constituent element Y of the above 111 semiconductor (1) is partially deleted.
, Yb-c, where the carrier concentration gradually and monotonically changes from the $1 semiconductor film (1) to the n-type semiconductor film (3), (7) is the structure of the above I1111 semiconductor 1) This region is composed of X-dYb with a part of the element X missing, and the carrier concentration gradually changes monotonically from the first semiconductor film (1) to the n-type semiconductor film (2), both clearly shown in the figure. However, in reality, the composition ratio changes continuously.

That is, since X - Y b is a material with a large E9 as described above, the carrier injection efficiency is low in the conventional structure, and it is extremely difficult to cause X - Y b to emit light. X-Yb-c in which the constituent element Y is partially missing has a carrier density higher than that of X-Yb, and therefore Il
X-Yb- in which the constituent element Y of l semiconductor (1) is partially deleted
The exchange of carriers between the region (6) composed of c and the n-type second semiconductor (3) is an X-Y region in which some of the constituent elements are missing.
This becomes easier than when there is no region (6) composed of b-c.

As mentioned above, since the composition ratio of Y changes continuously, the structure of the semiconductor II #i pole body of the embodiment of the present invention generally has a Fowler-Nordheim type tunnel,
The carrier migration barrier explained by Pool-Frenkel type, tunnel-induced collisional ionization, etc. is low, and therefore,
The exchange of carriers between the first semiconductor film (1) and the region (6) composed of XaYb-c in which some of the constituent elements of the first semiconductor film (1) are missing also becomes easy. Therefore, carrier exchange between the first semiconductor film (1) and the n-type second semiconductor (3) becomes easy.

Similarly, the first semiconductor g (1) and the first semiconductor film (1
) The exchange of carriers in the region (7) composed of X - a Y b in which some of the constituent elements are missing is also facilitated,
'The exchange of carriers between the M1 semiconductor film (1) and the P-type third semiconductor (2) is also facilitated.

In the embodiments of this invention, double heterojunction type LEDs have been described, but other types of LEDs may also be used.Here, a p-type semiconductor (2) is used as a material supporting a compound semiconductor (1).
Although the n-type semiconductor (3) is shown, the present invention is not limited to this, and may be a metal or an insulator, or may support only one side of the semiconductor electrode (1).

Example TiO2 (titanium oxide) is polymorphic and exhibits three types of crystal structures: rutile, anatase, and brutzite, and an amorphous structure.
T102-x, which is a semiconductor) and has some 0s missing, maintains its original structure and becomes a low-resistance semiconductor due to the contribution of 3d electrons. Here, we will discuss Ti(h) having the above-mentioned rutile structure. Rutile TiO2 is a low resistance n-type semiconductor. FIG. (1) is a TiO2 semiconductor.

(2) is a P-type third semiconductor, in which amorphous silicon is used; (3) is an n-type second semiconductor, in which amorphous silicon is similarly used here. (4) is a transparent electrode, (5)
is a power source, and (6) is a region in which a part of the constituent elements of the TiO2 semiconductor (1) composed of TiO2-8 is missing. T
E of iO2 is 3 eV, and the carrier injection efficiency is low in the conventional structure, making it extremely difficult to make TiO2 emit light. By the same action as above, T102-
Since the region (6) made up of X increases the injection efficiency, TiO2 emits light with a wavelength centered around 0-5 μm.

Since E9 is 3 eV, it originally emits light at a wavelength of 0.41 μ■, but in the structure of this example, an intermediate level is formed between the band gaps, so the center of one emission wavelength has changed to the longer wavelength side. It can be considered that

Note that, as represented by TiO2 used in the above example, when the oxygen composition ratio decreases from the original stoichiometric composition,
There are compound semiconductors that change into low-resistance n-type semiconductors by increasing carrier density while maintaining the same crystal structure. In this case, it is not necessary to form an n-type semiconductor, and high carrier injection efficiency can be obtained.

[Effects of the Invention] As explained above, the semiconductor electrode of the present invention includes a first semiconductor film made of two or more types of elements, an n-type second semiconductor film provided on one side of this I11 semiconductor film, and the above-mentioned first semiconductor film. In the device including a P-type II semiconductor film provided on the other side of the semiconductor film, at least the back side of the I11 semiconductor of the n-type (or p-type) semiconductor film has a part of the constituent element of the first semiconductor missing; By using a film characterized by a gradual monotonous change in carrier concentration from the I11 semiconductor film to the n-type (or P-type) semiconductor film, the efficiency of carrier injection into the semiconductor film can be increased. It is possible to obtain a semiconductor electrode body having a structure in which carriers are injected with high efficiency into a wide bandgap semiconductor having an E9 of 2.6 eV or more.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a semiconductor electrode body according to one embodiment of the present invention, JIZ diagram is a block diagram of a semiconductor electrode body according to another embodiment of the present invention, and FIG. 3 is a block diagram of a conventional semiconductor electrode body. It is. In the figure, (1) is a gi semiconductor film, (2) is a p-type third semiconductor film, (3) is an n-type second semiconductor film, and (6) is a part of the constituent elements of the first semiconductor (1). Deleted X -Y b -c
gII castle, (7) is the first semiconductor (1)
This is a region composed of X8-dYb in which some of the constituent elements are missing. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 1 t: Handle conductor wire z: P type part I tomo

Claims (1)

[Claims] A first semiconductor film made of two or more types of elements, an n-type second semiconductor film provided on one side of the first semiconductor film, and a p-type second semiconductor film provided on the other side of the first semiconductor film. At least on the first semiconductor film side of the n-type (or p-type) semiconductor film, a part of the constituent elements of the first semiconductor is missing, and the n-type (or p-type) semiconductor is removed from the first semiconductor film. A semiconductor electrode body characterized by a carrier concentration that gradually and monotonically changes toward the film.