JPS6269690A - Light emitting semiconductor device - Google Patents

Abstract

PURPOSE:To take out emitted light efficiently by a method wherein a non-single crystal semiconductor which contains small energy band widths is provided on a front electrode side and an effective energy band width of that semiconductor is made to be relatively large. CONSTITUTION:A P-type (m) or (n) semiconductor 13 is laminated on the 1st electrode 11 and a non-single crystal semiconductor 12, which is composed of alternately laminated silicon carbide or silicon nitride non-single crystal semiconductors, which are (n) semiconductors, and a plurality of (m) semiconductors, is formed on the (m) or (n) semiconductor 13. An N-type (m) or (n) semiconductor 21 is formed on the semiconductor 12. The non-single crystal semiconductor 12 is composed of (n) semiconductors 14, 16, 18 and 20 with wide Eg and (m) semiconductors 15, 17 and 19 with narrow Eg which are laminated together. The P-type semiconductor 13 and the N-type semiconductor 21 are used to provide ohmic contacts with electrodes and facilitate implantation of positive holes and electrons. Further, the 2nd electrode composed of an ITO film, which is a light transmitting conductive film, is laminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light emitting semiconductor device using a non-single crystal semiconductor.

The present invention is applied to multi-energy hands (hereinafter, energy bands or energy gaps are collectively abbreviated as Eg).
The present invention is characterized in that the non-single crystal semiconductors having different energy hand widths are stacked and provided.

In the present invention, a non-single crystal semiconductor sandwiched between two electrodes has m layers (m>■preferably m-2 to 200) within the semiconductor.
A non-single crystal semiconductor in a narrow (small) energy hand (
m semiconductor), one layer (n>2 preferably n=3~
201) and non-single crystal semiconductors (referred to as n-semiconductors) in a wide (large) energy hand are alternately stacked.

The present invention provides a non-single-crystal semiconductor whose main component is an element of group Ⅰ of the periodic table, in which the average thickness of one layer is 200λ or less,
Preferably, it has a laminated structure such as a superlattice (hereinafter referred to as SL) structure with a thickness of 30 Å or less, and the energy hand (Eg) of the m-semiconductor has a quantum effect due to the influence of the n-semiconductor sandwiching it. This effectively results in a large amount of Hg. This effectively increased Eg or the Eg that the semiconductor itself has is defined as the effective energy band ri.
It's called +.

The non-single crystal semiconductor in which the m-semiconductor and the n-semiconductor of the present invention are stacked on each other has a conduction band (hereinafter referred to as CR) of an energy band and a valence band at each boundary or boundary region of each semiconductor. The present invention relates to a light emitting semiconductor device having an energy band structure in which VB (hereinafter referred to as VB) is continuous or substantially continuous.

And CB of n semiconductor to CB of m semiconductor and VB
Or, the m-semiconductor forming this pocket has a pocket shape that is more energetically stable than VB, and the m-semiconductor located on the window electrode side is relatively Assuming a large effective Eg,
By making the effective Eg gradually smaller toward the inside,
The present invention is characterized in that the light generated by recombination in each pocket is prevented from being absorbed by the semiconductor itself located on the window side from the generation portion before being emitted to the outside by the window electrode.

Electrons and holes injected by applying a forward voltage to such pockets are accumulated, and the accumulated charges are recombined with each other, so that the emission wavelength for emitting light is not a specific wavelength but a wide emission wavelength range. It relates to producing continuous wave or white light emission.

The present invention has an ohmic contact between an electrode and a semiconductor (in the case of a PIN junction) or a Schottky junction in which a P or N type semiconductor is provided in close contact with an electrode, and electrons or holes, which are majority carriers in the junction, are Injected into a non-single-crystal semiconductor, electrons and holes pass through the n-semiconductor in this semiconductor by tunnel current or floor node current, and recombine between pan-dopants and band-recombine in the semiconductor that constitutes the energetic pocket of the m-semiconductor. The purpose is to cause recombination between centers, recombination center-to-recombination center, and to emit light.

By controlling the thickness of the m-semiconductor and n-semiconductor by forming them into a thin film laminated structure or a cluster laminated structure under manufacturing conditions, the m-semiconductor and n-semiconductor can be formed with an effective Eg value (m-semiconductor) in the middle of their respective energy bands. its own ug
). Therefore, continuous emission of visible light could be achieved by providing various thicknesses.

The present invention further provides an I-, N-, or P-type m-semiconductor having a narrower E than that of the n-semiconductors in these wide energy hands in this light-emitting region.
Wz Nt...WQ junction (q≧3.W: wide Eg
.

semiconductors (N: semiconductors with narrow Eg) are stacked, and further junctions such as III, PIN, pH, or IIN junctions are successively made as CB and VB, and their Eg
C
The purpose is to emit light by recombining electrons, holes, etc. between B and VB.

Conventionally, compound semiconductors having a single crystal structure such as GaAs are known as light emitting elements. In this method, a forward current is passed through the PN junction, and the recombination of electrons and holes at the junction is used to emit light of a specific wavelength.

Furthermore, in order to apply such a light emitting element to a non-single crystal semiconductor, the patent application "Semiconductor device J.
(53-1,02517) (S53.8.23 application), “Light Emitting Semiconductor Device J (56-19900) (3
56, 2, 13 application) (56--139263) (S
56.9.4 application). The present invention is a further development of the single heterojunction or double heterojunction type semiconductor device using a non-single crystal semiconductor filed by the inventor.

The present invention is not directed to one or two such heterojunctions;
It has a multi-heterojunction structure of three or more,
Patent application 58-160026 (5
8, 8, 30) are known. This invention is N-W-N
A PIN junction is provided.

The present invention is a further development of this invention. In this multi-heterojunction, in order to efficiently extract emitted light to the outside, at least one electrode is made translucent, and preferably the other electrode is made reflective. Furthermore, the non-single crystal semiconductor sandwiched between these two electrodes is a Schottky junction or a heterojunction.

The non-single crystal semiconductor used in the present invention is mainly composed of silicon or germanium to which hydrogen or a halogen element is added. The n-semiconductor, which is a non-single-crystal semiconductor with a wider energy band width, is a compound (mixture) of silicon and carbon, 5iXC+-g (0≦x<1) or 5iJ4□ (0
≦X〈4), and for m semiconductors, 5iyC+-y
(0<Y<1) However, x x y, that is, m semiconductors are C and N
We mainly used conditions where the amount of addition was large.

And the m semiconductor is a window electrode 9 at NI+NZ+...NQ-+! In I (hereinafter, for simplicity, I, 2, . . . , the smaller number of q will be referred to as the window side), the added amount of carbon was set to be large, that is, the value of y was set to be smaller.

Furthermore, as another structure, the n-semiconductor is W,, W2...
In K1++Wq, the addition amount of carbon, nitrogen or oxygen is increased in the window side surface electrode (hereinafter, for simplicity, the one with the smaller number of 1, 2...Q-1, Q is the window side), that is, X The condition is that the value of is smaller.

An embodiment of the semiconductor device of the present invention will be shown below based on FIG.

Example 1 In FIG. 1(A), a non-single crystal semiconductor (12) having a multi-heterojunction is converted into an amorphous semiconductor (AS) doped with hydrogen or fluorine, or a semi-amorphous semiconductor (S).
AS), a polycrystalline semiconductor (C3), or a semiconductor having a transition structure.

SAS is As in a broad sense having crystal grains or crystallinity having a lattice strain on the order of 5 to 100 short ranges. That is, it is a mixture of an amorphous structure and a crystalline semiconductor, and its free energy is intermediate between that of AS and a crystalline semiconductor. Since the present invention uses a non-single crystal semiconductor, particularly a semiconductor having a crystalline or amorphous structure with extremely small grain size and lattice strain, the transition of light is presumed to be a direct transition unlike that of a single crystal.

In the present invention, such a non-single crystal semiconductor is formed on a substrate of glass, ceramic, or a transparent organic thin film insulator using a transparent conductive electrode (11) made of tin oxide or tin oxide on ITO.

On the first electrode (11), a P-type m or n semiconductor (Step 3), a silicon carbide or silicon nitride non-single crystal semiconductor (13), and a plurality of m semiconductors are alternately stacked. It has a non-single crystal semiconductor (12). Furthermore, an N-type m or n semiconductor (21) is provided on this semiconductor.

Non-single crystal semiconductors (12) are n-semiconductors with wide ER (here, (14), (16), (18), (20)
) ) and narrow Eg m semiconductors (here (15), (
17) and (19)). Both the P-type semiconductor (13) and the N-type semiconductor (21) were used for ohmic contact with the electrodes to facilitate the injection of holes and electrons. Furthermore, a second electrode made of ITO, which is a transparent conductive film, was laminated.

This non-single crystal semiconductor (12) is composed of an n semiconductor and an m semiconductor with n = 1 (14), m = 015), n = 2 (1
6), m = 2 (17).

n −3 (18), m = 3 (19), n = 4 (
20) and 2 to 30 layers each having an average thickness of 200 Å or less, preferably 2 to 30 layers. Then, if these are made extremely thin, a part or whole of them will have a multilayer laminate structure, which can also be called an SL tank structure, and the thickness of m
It becomes possible to make the energy band width of the semiconductor to be in an effective energy band that is larger than the value that the semiconductor itself has.

As a result, it has the characteristic that the energy band width for visible light, particularly short wavelength visible light, can be made to have large electrical conductivity relatively easily. And in the effective energy band of m semiconductors (41), (42)
, (43) should be near the window or as large as possible Eg(41)>
Eg> (42) >Eg (43).

By stacking non-single crystal semiconductors using the method described above, it has become possible for the first time to continuously vary the energy hand.

Furthermore, in the present invention, in order to neutralize dangling bonds in the non-single crystal semiconductor, a halide such as hydrogen or fluorine is contained in an amount of lat% or more, for example, 15at% (II), and furthermore, carriers in Eg are contained. This further reduces the recombination center density and prevents its increase.

For this reason, specific recombination centers (N
ss ) does not exist, and both CB and VB have smooth energetic continuity (continuity) (due to microscopic non-uniformity of stoichiometric ratio, there is Since a barrier has no effect at all, in the present invention, even the presence of such a microscopic barrier is referred to as continuous), which is completely favorable for electrons and holes.

Furthermore, in the present invention, silane (Si
pHzr+z P≧1), silicon fluoride (Sih, 5izF
6 Other silicide gases were used. Furthermore, if necessary, SiH4, -V(CH3)yy = 1 to 4 or 5i
z(Cll:+)Vl16-11n-1 to 5 or Cy
tl z such as Czllz, CzlL were added as additives to modify Eg. These reactive gases are processed by photoplasma vapor phase reaction method (PCVD) using glow discharge method.
method), Photo CVD method, Photo plasma 7 CVD method (PP CVD method), l0M0 (LT)
They were decomposed and reacted by a CVD method such as a CVD method to produce m-semiconductors and n-semiconductors on a substrate. As a non-single-crystal semiconductor with a narrow energy band width of m-semiconductor, no or substantially no impurities are added (impurity concentration 10110l7' or less), and intrinsic or substantially intrinsic 5iyC+-y (0<Y≦1 ) was used.

Furthermore, a wider [! 5ixC+-X (0≦X<1) or Si with g,
It was manufactured using a similar CVD method using semiconductors such as N and -x. SiH4,- as a starting material for semiconductors with a wide E
,, (CH3)nn-1 to 4 or 5i2(CH+)n
The reaction was carried out using methylsilane with H, -n = 1-5. Furthermore, Eg produced by this methylsilane
Non-single crystal semiconductors with smaller Eg are methylsilane and silane (StHn).

Plasma glow discharge method of mixed gas with Si□)16),
5ixC+-x+ (0<X<1) (1,7eV<
Eg<3.5eν) was mainly utilized. DM here
S (■ gsi (CH3) z (dimethylsilane)
was used as a starting material without adding any impurities. Then, this 5ixC,, (0<X<l Eg =2.3~3
．． 2 eV) was obtained. As this n semiconductor, 5isN
In order to obtain 4-x, SiH4 and NH were produced by a glow discharge method while varying the mixing ratio. Or Siz! I6,5i
It may also be produced by a photo-CVD method by mixing zF6, N)Is, and Nz+Hz. Further, to these n-type semiconductors, a valent or v-valent impurity such as B or P using diborane as a P-type or N-type impurity may be added simultaneously with the silicide gas or methylsilane. In this way, the m-semiconductor and n-semiconductor were stacked together as shown in FIG. 1(A) to form a non-single crystal semiconductor sandwiched between two electrodes.

After this, the upper electrode (22) was formed.

Here, a P-type semiconductor (13), a multi-band cap semiconductor (12), and an N-type semiconductor (21) were fabricated using the photo-CVD method according to the above-described order. That is, on the introduction side of the reactor, disilane as a silicide gas, a P-type impurity gas, an N-type impurity gas, and an additive such as DNS, ammonia, or Nt+Hz were arranged together with a carrier gas.

The reaction system is forcibly evacuated from the exhaust system using a turbo molecular pump to achieve a reduced pressure state, and the pack ground level is
X 1O-8 torr or less. Further, a reactive gas is introduced to increase the pressure to 20 to 0.001 torr, e.g. 3 torr.
The pressure was reduced to r. A substrate is placed in this reactor in advance, and the energy density is set at 30 mW/cm2 in order to radiate 184 nm ultraviolet light onto the substrate heated to room temperature to 500°C, typically 200 to 300°C, or in front of and near the substrate. (
A total amount of 184 nm and 254 nm) is added using a low-pressure mercury lamp to cause a photochemical reaction in the reactive gas in the reactor. This optical excitation energy chemically activates, decomposes or reacts the above-mentioned reactive gas to form a film on the surface of the substrate.

Unwanted materials and used carrier gas were discharged from the exhaust system to the outside via a turbo molecular pump.

This photo-CVD method is used to make the m-semiconductor a non-single-crystal semiconductor, and the Eg of the semiconductor located on the window side is increased to a large Eg.
I made it so that Furthermore, the silicide gas was completely evacuated and DMS was introduced, and n semiconductors for W-E8 were laminated alternately with m semiconductors so that the window side had a large Eg.

This fabrication can be carried out by switching the introduction of reactive gas.
Semiconductors and n-semiconductors were alternately stacked on each other.

This junction or boundary region of different conductivity types has a film growth rate of 0.001 to 10 people/sec, for example 0.1 people/sec, and in addition, the thickness can be controlled by optical CVD.
Lower the lamination pressure (1 to 0.01 torr, e.g. 0.
5 torr) to form a thin film layer.

That is, the average film thickness of m and n semiconductors is 10, 30,
50 or 80 people, depending on the film formation time. The average thickness of each film is 100 Å or less, preferably 30 Å.
By making the thickness less than Å, the interaction between the m-semiconductor and the n-semiconductor is increased (Eg is set to 2.5 to 3
．． 2 eV) (thickness is preferably 2 to 30 people) to a small state (Hg of 1.7 to 2.5 eV) (thickness of 30 to 2
00 people).

In the present invention, the stoichiometric ratio of the m-semiconductor itself is varied as described above, and the amount of DMS to disilane is increased in the m-semiconductor ((15) in FIG. 2) on the window electrode (11) side. Eg, and in the m semiconductor (19) on the back electrode (21) side, the amount of DMS is reduced to create a narrow Eg.
That is. As a result, the m-semiconductor has a small quantum amount of SL (and a narrow Eg).

As a result, the m-semiconductor, combined with the quantum effect of SL, reduces the absorption reduction on the back side, and also emits light with a short wavelength on the window electrode side, and light with a long wavelength inside. The light is absorbed by the semiconductors on the window side, preventing it from becoming heat.

The present invention takes advantage of and implants such properties.

For carriers, the n-semiconductor forms a barrier and traps the carriers in the m-semiconductor. Furthermore, the Eg of silicon carbide, which is a non-single-crystal m-semiconductor, is modified by the amount of carbon added thereto, and expanded by the n-semiconductor, increasing its Eg to 2.3 to 3.
At 5 eV, visible light is emitted mainly through band-to-band transition. In order to inject carriers for that purpose, the third and fourth semiconductors are connected to two electrodes, for example, the energy band of the P-type semiconductor (13) in contact with the window side is made to be in the P-type head direction (17゛). Indium oxide or IT that makes the energy band width of the fourth N-type semiconductor (21) tend to be N-type
P (13) I (1
2) Achieved between N(21) junction and electrodes (11) and (31).

Of course, the third semiconductor (13) is a P type, and in order to prevent light absorption by impurities, it is preferable to use an N semiconductor, or by removing this semiconductor, a Schottky diode or SL type diode structure can be created. good.

FIG. 2 shows the energy band width corresponding to FIG. 1(A) and also shows its operating principle.

In the drawing, a first transparent conductive film made of tin oxide (11) is provided on a substrate (30). On top of this, a non-single crystal semiconductor (12) having an SL structure (Rg = 1.7 ~
3.3 eV). A P-type third semiconductor (13) and an N-type fourth semiconductor (21) are provided as current injection media with this non-single crystal semiconductor sandwiched therebetween. Further, on the back side, there is a transparent electrode (13) (reflective electrode (22) such as AI, A, etc.).In other words, one side is made of tin oxide and the other is ITO, which is a PIN junction.Of course, one or both of these electrodes are made of tin oxide and ITO. may have a Schottky junction configuration.

Furthermore, this non-single-crystal semiconductor (12) is formed by m-semiconductor (
15), (17), (19) are provided, and n semiconductors are provided (14), (16), (1B),
(20). The average thickness of each group was set at 2 to 200 people. Then, the optical energy band width becomes CB (25) substantially (24) D, and V
B (23) is substantially changed and modified to D (24).

Visible light (6) moves forward as shown in Figure 2 (B).
Adding a 20V bias (29), electrons (28)
(Hole (27) was injected from each electrode and observed.

Furthermore, in order to improve the luminous efficiency, a reflective electrode (22) on the back surface is provided from silver or aluminum.

Therefore, the light emitted toward the back surface passes through a transparent electrode made of ITO (indium tin oxide) and is reflected at the electrode (22), thereby generating reflected light (32).

That is, by constructing a multilayer stack as in the present invention, visible light emission could be achieved using only silicon, carbon, and nitrogen, which exist in large amounts on the ground, other than III--V compounds, as the main components.

Of course, it is not an interband transition as shown in Fig. 2, but a transition between a band and a recombination center. The charge from the recombination center is also a single crystal semiconductor, and the recombination center is 10I8 (101
It was observed at the same time because it was less than 5-10 Ia) cm-''.

Of course, FIG. 1A and FIG. 2 show the m-semiconductor in three layers and the n-semiconductor in four layers. However, the number of m + n may be 2 to 200.2 to 201 layers, and it goes without saying that it may be 200 or more layers if technically possible.

Example 2 FIG. 1(B) is another embodiment of FIG. 1(A).

That is, in FIG. 1(B), the m and n semiconductors (12) constituting the transition region have an average film thickness of 30 Å or less, for example, 2 to 8 people, and considering the process, it is difficult to form a continuous flat surface. Rather, a lump-like cluster is formed on the first electrode (12), and other cluster-like n semiconductors are formed so as to surround the rask-like m semiconductor and form a pocket-like energy band. They are stacked on top of each other,
A second electrode (14) is further laminated thereon.

The rest is the same as in Example 1. Such structure (3) and m
Because the semiconductor is electrically divided within one layer,
There is little adverse effect (surface leakage) on the peripheral surface.

This FIG. 1(B) is electrically equivalent to FIG. 2(A). It goes without saying that a portion in between may have a cluster-like structure, and a portion in the middle may have a thin-film structure.

In the drawings, the thickness of this semiconductor and the number of m-semiconductor and n-semiconductor layers can be changed according to design specifications.

Example 3 FIG. 3(A) shows another embodiment of the present invention.

FIG. 3(^) shows an energy band diagram of the present invention.

In this drawing, m semiconductors (15), (17)
, (19) have the same stoichiometry. St or 5
ixC+-x (0≦<1) is (15), (17
) and (19) are constant.

However, n-semiconductors (14), (16), (18)
, (19) has its stoichiometric ratio varied. And Eg on the window side surface electrode (11) side is increased. That is, if it is an n semiconductor, 7SisNn-++ (0<X<4
). However, for example (14), X = 0.4.
(16) is x = 0.8. (18) is x = 1.2
．． (20) is x=1.6. By doing so, if the m-semiconductor is made to have a thickness of 30 Å or less where the SEL effect occurs, the effective energy band width can be set such that Eg is large on the window electrode side and becomes smaller as it goes inside.

The other aspects of the third embodiment are the same as those of the first embodiment.

Example 4 This example, whose energy band width is shown in FIG. 4, is a combination of Examples 1 and 3.
Although 5ixC+-x (0<X4) for a semiconductor, the value of X is, for example, (15) x=0.3.
(17) is x = 0.4. (19) assumes x = 0.6.

In addition, in S'rffNa-x for n semiconductors (
14) is x = 0.4. (16) is x = 0.8.
(1B) is x = 1.2. (20) is set to X-1,6.

In this way, the effective energy band width can be gradually decreased from a wide energy band width to a narrow energy band width toward the inside from the window electrode side.

In this case, in order to use two parameters during film formation,
Reliability is poor. However, it is possible to more precisely make the window side have a large energy band width. In particular, the amount of conduction band or valence band of each of the m-semiconductor and the n-semiconductor can be made constant, and the same energy is required to jump over the n-semiconductor serving as a barrier in any pocket.

Furthermore, by controlling the position over which this barrier is jumped, it will be possible to adjust the emission intensity at each wavelength to a predetermined distribution, such as a solar spectrum distribution. Example 3
The steps are the same as in Example 1.

Furthermore, the present invention has been described using group (I) elements as main component semiconductors.

Furthermore, in order to obtain that wide Pg, 5ixC+-x O<
x1) was mainly used. However, as an m semiconductor, G
e as n semiconductor, 5ixGe, -3(0< x
It goes without saying that <1) may be applied to that purpose and used as part of one or both semiconductor layers or an intermediate third semiconductor layer.

The present invention is represented by providing one semiconductor on a substrate as shown in FIG. However, it can also be used as a surface light source, or by selectively selecting edges to obtain a surface that emits letters, numbers, and symbols.Also, the upper electrode can be formed into a matrix, and an external control device can be used to control the light emitting element device of the TV display. It goes without saying that this is a good idea.

In addition, by controlling the Eg of this boundary, the degree of doping of impurities, or the amount of additives that adjust Eg, it is possible to emit continuous light or white light whose wavelength is visible light instead of light of a specific wavelength. Has characteristics.

Furthermore, the energy band diagrams in FIGS. 2 and 3 do not show their absolute values, but simply show the relative magnitudes and positional relationships of Eg of each semiconductor.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional view of a semiconductor device of the present invention. FIG. 2 shows an energy band structure illustrating the operating principle of the invention. 3 and 4 show other embodiments of the invention.

Claims (1)

[Claims] 1. In a light emitting semiconductor device having a first electrode, a non-single crystal semiconductor, and a second electrode on a substrate, the non-single crystal semiconductor includes a plurality of non-single crystal semiconductors having a large energy band width. A single crystal semiconductor and a plurality of non-single crystal semiconductors each having a small energy band width are alternately stacked, and the non-single crystal semiconductor having the small energy band width is provided on the front electrode side on one window side of the electrode. An issuance semiconductor device characterized in that the effective energy band width of the semiconductor is provided to have a relatively large energy band width. 2. In claim 1, the effective energy band width of the non-single crystal semiconductor to which hydrogen or halogen elements having a small energy band width are added is determined by changing the stoichiometric ratio of the semiconductor to a surface electrode on the window side. A light emitting semiconductor device characterized in that the energy band width provided on the side is increased. 3. The light emitting semiconductor device according to claim 2, wherein the stoichiometric ratio of the semiconductor is changed by increasing the amount of carbon and nitrogen added to the silicon semiconductor to increase the effective energy band width. 4. In claim 1, the effective energy band width of the non-single crystal semiconductor to which hydrogen or halogen elements having a large energy band width are added is determined by changing the stoichiometric ratio of the semiconductor to the surface electrode on the window side. A light emitting semiconductor device characterized in that the effective energy band width provided on the side is increased. 5. The light emitting device according to claim 4, characterized in that the semiconductor having a large energy band width is provided by increasing the amount of carbon, nitrogen, or oxygen added to silicon when forming the semiconductor. Semiconductor equipment. 6. In claim 1, in order to form an ohmic contact with the non-single crystal semiconductor provided by stacking the non-single crystal semiconductor, a P or N type non-semiconductor is provided between the first electrode and the non-single crystal semiconductor. A single crystal semiconductor is provided, and N is provided between it and the second electrode.
Alternatively, a light emitting semiconductor device comprising a P-type non-single crystal semiconductor.