JPH02230777A - Surface light emitting type variable wavelength light emitting element - Google Patents

Abstract

PURPOSE:To obtain a surface light emitting type light emitting element capable of tuning light wavelength by stacking, on a semiconductor substrate, a first semiconductor lamination structure body and a second semiconductor lamination structure body with piezo effect. CONSTITUTION:A first semiconductor lamination structure body is constituted of semiconductor layers 12, 13, 14. A second semiconductor lamination structure body is constituted of semiconductors 14, 15, 16. A multilayer film 17 constituted of two periods of Si/SiO2 has reflectivity R=90% in a wavelength region of lambda=1-1.6mum. In the case of four periods, R=95% can be obtained. A part of a substrate 11 is eliminated: the first and the second semiconductor lamination structure bodies where the substrate is eliminated are formed as active regions: these regions are an element structure where light radiated from the light emitting layer 13 is subjected to reflection.interference between the multilayer film 17 and a P-clad layer 12. When the effective length of the second lamination structure body is changed, the effective length of the total element also changes, thereby tuning the wavelength of the emitted light. In order to change the effective length of the second lamination structure body, the piezo effect is used.

Description

[Detailed description of the invention] [Industrial application field] The present invention is used in optical communication and optical information processing, and is a surface-emitting type variable device in which light is input and output in the surface direction, and the emission wavelength can be tuned when emitting light. This invention relates to a wavelength light emitting device.

[Conventional technology]

The surface emitting type light emitting element is, for example, something like a surface emitting LED (light emitting diode). In such devices, if the emission wavelength can be controlled, parallel optical transmission and optical processing using wavelength multiplexing can be realized.

As a surface-emitting type light-emitting element whose emission wavelength can be tuned, the one shown in FIG. 2 is known. Aitulpurui Journal of Quantum Electronics (I
EEE Journal of QuantumEle
ctronics) Volume QE-22, No. 9, 1984
It is reported on pages 1682 to 1695 of 2016.
It is usually called the n-i-p-i structure. In this structure, n-type, i-type, and p-type semiconductor layers are repeatedly stacked in order. In this example, electrons and holes are excited in the conduction band and valence band by photobombing. Excited carriers generate light and recombine through a radiative recombination process.
The peak emission wavelength changes depending on the bending state of the band.

[Problem to be solved by the invention]

There are two problems with this element. One is that when the number of excited carriers exceeds a certain level, the peak wavelength hardly changes, and the other is that the emission intensity is weak. Considering actual applications, it is desirable to excite carriers by current injection, but similar problems occur even in that case. When a voltage is applied to the p-type and n-type semiconductor layers using the current injection method and carriers are injected by applying current, initially the band bends and the emission wavelength changes in response to the applied voltage. , the luminescence intensity is very weak. This is because the amount of injected carriers in this state is extremely small.

To obtain sufficient light emission, a voltage corresponding to the built-in voltage must be applied to inject a large number of carriers. However, in this state, the wavelength hardly changes. Built
This is because when the in voltage is reached, the voltage across the pn junction is clamped there, and the band structure hardly changes. In other words, it has not been possible to ensure sufficient emission intensity and tune the wavelength in such a state.

An object of the present invention is to provide a surface-emitting light emitting element that allows wavelength tuning while maintaining sufficient emission intensity.

[Means to solve the problem]

The surface-emitting variable wavelength light emitting device of the present invention has a first semiconductor layered structure including a pn junction, and a layer made of a material having a piezoelectric effect or a second semiconductor layered structure on a semiconductor substrate. An electrode for current injection is formed in the first semiconductor multilayer structure, an electrode for voltage application is formed in the layer or the second semiconductor multilayer structure, and The structure is characterized in that it outputs light.

[Effect]

The first semiconductor stacked structure of the two stacked R structures acts as a surface-emitting type light emitting diode. A voltage is applied to the second laminated horizontal body to change the effective length (in the direction perpendicular to the layers). A piezo effect or the like is used as a mechanism for changing the effective length of the second laminated structure. The two stacked structures together form and function as one variable wavelength light emitting device.

Next, the principle of changing the emission wavelength will be explained. It is known that in surface-emitting light-emitting diodes, a light resonator effect occurs due to multiple reflections between the light extraction surface and the back surface, and the spontaneous emission spectrum contains a pattern of intensity similar to that immediately before oscillation of a laser diode. It is being This phenomenon becomes more pronounced as the light emitting diode becomes thinner. Peak wavelength ^.

are the distance d between the light extraction surface and the back surface, the effective refractive index nr,
Using an integer N, 2n, λ. =Nd-(1).

In the present invention, in order to widen the peak wavelength interval, the thickness d of the entire variable wavelength light emitting element including the semiconductor substrate is made considerably thinner than usual. Normally, surface-emitting diodes
The element thickness is almost the same as that of a semiconductor substrate, approximately 10
It is about 0 μm. Compared to this, the present invention reduces the thickness of the substrate by 1
Keep it as thin as possible. Or a first semiconductor stacked structure,
An electrically insulating layer and a second semiconductor laminated structure are formed in this order on a semiconductor substrate, and a semiconductor multilayer film with a high reflectance is formed between the substrate and the first laminated structure. With this structure, there is no need to make the semiconductor substrate thinner. In any case, by reducing the element thickness in this way, the interval between the peak wavelengths determined by equation (1) can be widened; Only books can be generated. If both end faces of the entire variable wavelength light emitting element have a certain degree of finesse, spontaneous emission light with a narrow spectral width determined by this finesse can be obtained. Here, the second
By changing the effective length of the laminated structure, the effective length of the entire device also changes, making it possible to tune the emission wavelength. The Viezot effect is used to change the effective length of the second laminated structure.

In this case, A 12 G a As / G a A
The lattice strain of s-system and InGaAsP/InP system is 1 2
It is approximately 1% at an electric field of 0 kv/cm. However, in order to make the Viezot effect appear in the direction of the electric field, it is necessary to select an appropriate plane orientation. If the thickness of the variable wavelength light emitting element is d, the thickness of the second laminated structure is d2, the change due to the piezo effect is δd2, the emission peak wavelength is ^d, and the change is δλ, then Q k v / cm The electric field is d2=1 μm, which is 12V when converted into voltage. At this time, the wavelength change can be shifted by 0.3%, that is, by 4.5 people, if the material system of formula (2) is also selected as InGaAsP/InP and the emission wavelength is 1.5 μm.

〔Example〕

FIG. 1 shows an embodiment of the present invention. In this example, a p-InGaA film which serves as a stop etch layer and a p-cladding layer is placed on a p-InPll of a substrate with a plane orientation (111).
sP layer 12 (λ81.15 μm, thickness d=0.3 μm,
Carrier concentration N=2X 1018cm-3), Ino47G a 0.53A S layer 13 which becomes the light emitting layer
(λg = 1.67μm, d1μm, undoped), n-In that serves as an n-cladding layer and contact layer
GaAsP layer 14 λ = -1.15 μm, d = 1 μm,
N=2X1018cm-”), I n 0 of Andove
．． 52A. 1 0. 4BA S layer 15 (d=1μ
m), n-InGaAsP layer 16 (
λR=1.15, um, d=0.2μ m, N=
2X10 l8cm-3), Si (
A multilayer film 17 in which d=890 people) and Si○2 (d=2155 people) are alternately stacked is sequentially stacked, and the semiconductor layers 12, 13, and 14 form the first semiconductor stacked structure, and the semiconductor layers 14, A second semiconductor stacked structure is formed in steps 15 and 16. The multilayer film 17 is Si/Si○ with a period of 22^-
The reflectance can be R=90% in the wavelength range of 1 to 1.6 μm, and R-95% in 4 cycles. As shown in FIG. 1, a part of the substrate is removed, and the first and second semiconductor laminated structure parts in the area where the substrate is removed are used as active regions, and the light emitted by the emission N13 is transferred to the multilayer film and the p- The element structure is such that reflection and interference occur between the cladding layers 12. 18 and one are AuGe electrodes.
- Made of Ni. 20 is an electrode made of AuZn.

The emission wavelength is about 1.5 μm, and when R=0.95, F=122.

The peak wavelength can be found from equation (1), but in this case, nr=
3-5, d=3.5 μm, so λ. ? At 3 ^. -1.5μm, N=4, ^A 2μm, so In (3. 47G a 0.93A S 1
The peak wavelength can be set near the emission wavelength of No. 3. The width of the emission vector Δνl7■ is the peak wavelength interval Δ
From ν and ΔFrayness F, we get Δν1/■V■, so there are approximately 41 people F. To tune with a narrower spectral width, it is possible to reduce absorption loss and oscillate the laser in the plane direction. The basic structure may be the same as the embodiment shown in FIG.

The wavelength tuning is performed using the electrode 2 as shown in Figure 1.
0 is connected to a positive power source, electrode 18 is connected to a negative power source, electrode 19 is connected to ground, and Ino. 47G ao. 53A s
1 3 to emit light, L no. 52
A. This is done by applying an electric field to 10.48A S 1 5 and performing piezo modulation. I no. s2Afflo. 4BAs
15 becomes a high resistance layer in an undoped state, and an electric field can be applied thereto.

In the embodiment shown in FIG. 1, the p1nP11 of the substrate is etched.
is taking. If a semiconductor multilayer film is formed between the p-InGaAs P 12 and the substrate and this is used as a reflecting mirror, such etching of the substrate becomes unnecessary.

〔Effect of the invention〕

According to the present invention, a surface-emitting light emitting element whose emission wavelength can be tuned can be obtained. It goes without saying that other materials than those used in this example, such as GaAs, may be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing a conventional example. 11 is p-InP, 14 and 16 are n-InGaAsP,
13 is I n (3, 47G a 0.53AS,
12 is p-InGaAsP, 15 is I n 0. 52
A 1 0. 48As, 17 is a multilayer film, and 18, 19, and 20 are electrodes.

Claims (1)

[Claims] A first semiconductor laminated structure including a pn junction and a layer made of a material having a piezo effect or a second semiconductor laminated structure are laminated on a semiconductor substrate, and the first semiconductor laminated structure A surface emitting device characterized in that an electrode for current injection is formed, an electrode for voltage application is formed on the layer or the second semiconductor laminated structure, and light is output in the direction of the semiconductor lamination. Variable wavelength light emitting device.