JPH06283761A - Znse blue light emitting diode element - Google Patents

Abstract

PURPOSE:To provide a ZnSe blue light emitting diode element large in light emission intensity. CONSTITUTION:This element comprises an n-type GaAs single crystalline substrate 1, an n-type ZnSe layer 2 made on that single crystalline substrate 1, and a p-type ZnSe layer 3 made on that n-type ZnSe layer 2, and this n-type ZnSe layer 2 serves as a light emitting layer, and also the concentration of that n-type carriers is larger than 1X10<17>cm<-3> and smaller than about 5X10<17>cm<-3>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ZnSe (zinc selenide) blue light emitting diode element, and more particularly to a ZnSe blue light emitting diode element having high emission intensity.

[0002]

2. Description of the Related Art ZnSe, which is a II-VI group compound semiconductor, has a wide bandgap of direct transition type and is capable of emitting light from ultraviolet light to blue light and green light. Currently, active research is being conducted on light emitting diode devices using this material.

Such a light emitting device is disclosed in, for example, Japanese Patent Laid-Open No. 63-18.
No. 5077 (H01L 33/00) and the like.

[0004]

However, the conventional ZnSe blue light emitting diode element has a problem that sufficient emission intensity cannot be obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a ZnSe blue light emitting diode element having a large emission intensity.

[0006]

A ZnSe blue light emitting diode device according to the present invention comprises a first conductivity type single crystal substrate, a first conductivity type ZnSe layer formed on the single crystal substrate, and a first conductivity type ZnSe layer. A ZnSe blue light emitting diode element comprising a ZnSe layer of a second conductivity type, which is a conductivity type opposite to the first conductivity type, formed on a ZnSe layer of a conductivity type, wherein the ZnSe layers of the first and second conductivity types are provided. ZnS whose conductivity type is n-type among the layers
The e layer becomes a light emitting layer and the n-type carrier concentration is 1 ×
It is characterized in that it is larger than 10 ¹⁷ cm ^{-3 and} is approximately 5 × 10 ¹⁷ cm ^-3 or less.

In particular, among the first and second conductivity type ZnSe layers, the carrier concentration of the ZnSe layer whose conductivity type is p-type is set to 1 × 10 ¹⁷ cm ^-3 or more to 4 × 10 ¹⁷ cm ^-3 or less. It is characterized by

[0008]

Operation: The carrier concentration of the n-type ZnSe layer is 1 × 10 ¹⁷ c
When the n-type ZnSe layer is used as a light emitting layer by setting it to be larger than m ^{−3 and about} 5 × 10 ¹⁷ cm ⁻³ or less, the emission intensity of the ZnSe light emitting diode element increases. Particularly, the carrier concentration of the p-type ZnSe layer is from 1 × 10 ¹⁷ cm ⁻³ to 4 × 10 ¹⁷
In the case of cm ⁻³ or less, the n-type ZnSe layer becomes a particularly favorable light emitting layer.

[0009]

EXAMPLE A ZnSe blue light emitting diode element according to an example of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view schematically showing the structure of a ZnSe blue light emitting diode element of this example.

In the figure, 1 indicates a carrier concentration of 1 × 10 ¹⁸ cm
^{-3 to} 2 × 10 ¹⁸ cm ^-3 n-type GaAs single crystal substrate 2, 2 has a layer thickness of 1 μm or more formed on the single crystal substrate 1, for example, a layer thickness of 2 μm, and is a chlorine-doped n-type ZnSe layer (emission). Layer), 3 is a layer thickness 1 formed on the n-type ZnSe layer 2
μm or more, carrier concentration 1 × 10 ¹⁷ cm ⁻³ or more, for example, layer thickness 2 μm, carrier concentration 1 × 10 ¹⁷ to 4 × 10 ¹⁷ cm
^-3 is a p-type ZnSe layer with nitrogen added.

A p-type side electrode 4 and an n-type side electrode 5 are formed on the p-type ZnSe layer 3 and the lower surface of the single crystal substrate 1, respectively.

An example of a method of manufacturing such an element will be shown below.

The n-type ZnSe layer 2 and the p-type ZnSe layer 3 are epitaxially grown by a molecular beam epitaxial growth method (MBE method).

First, the substrate temperature of the n-type GaAs single crystal substrate 1 is set between 240 ° C. and 350 ° C., and simultaneously with Zn (metal zinc) molecular beam and Se (metal selenium) molecular beam in ultrahigh vacuum. The n-type GaAs single crystal substrate 1 is irradiated with a CdCl ₂ molecular beam to form a chlorine-added n-type ZnSe layer 2.

Then, a nitrogen (N ₂ ) radical is formed on the n-type ZnSe layer 2 by exciting a N ₂ (nitrogen molecule) gas at the same time as a Zn molecular beam and a Se molecular beam by high-frequency discharge of the N ₂ molecule. P-type Z with nitrogen added by irradiating a beam of
The nSe layer 3 is formed.

Thereafter, a p-type side electrode 4 and an n-type side electrode 5 are formed on the p-type ZnSe layer 3 and the lower surface of the single crystal substrate 1, respectively, by using a vacuum evaporation method or the like.

FIG. 2 shows the blue emission intensity and n-type Zn of such a device.
It is a figure which shows the relationship of the carrier concentration of Se layer 2. The applied current I _F is 3 mA, and the carrier concentration of the p-type ZnSe layer 3 is 1.5 × 10 ¹⁷ cm ⁻³ as an example.

From this FIG. 2, such a device has an n-type ZnSe layer.
Carrier concentration of 2 is 9 × 10¹⁷cm ^-3Almost above neighborhood
Does not emit light, but is approximately 5 × 10¹⁷cm^-3The emission intensity is
It turns out that it will grow significantly. Although not shown,
The carrier concentration of the p-type ZnSe layer 3 is 1.5 × 10 5
¹⁷cm^-3Not limited to 1 × 10¹⁷cm^-34 × 10 or more¹⁷c
m^-3Within the following range, the capacity of the n-type ZnSe layer 2 is
Rear concentration is about 5 × 10 ¹⁷cm^-3If the following range
Then, holes are formed from the p-type ZnSe layer 3 to the n-type ZnSe layer 2.
The n-type ZnSe layer 2 is particularly good because it is injected efficiently.
And functions as a light emitting layer to increase the emission intensity.

FIG. 3 shows the n-type ZnSe layer 2 of such a device.
3 shows the relationship between the blue emission intensity and the applied current I _F when the carrier concentration of is changed.

From this FIG. 3, such a device has an n-type ZnSe layer.
Carrier concentration (n) of 2 is 9 × 10 ¹⁷cm^-3Above neighborhood
Is the applied current I_FEven if it is set to a large value, it hardly emits light,
Rear concentration (n) is approximately 5 × 10¹⁷cm^-3Below is the emission intensity
And applied current I_FIs approximately proportional to increasing the applied current
It can be seen that a larger emission intensity can be obtained.

2 and 3, and the n-type ZnSe layer 2
Carrier concentration is 1 × 10¹⁷cm^-3The element resistance
Since the resistance is increased, the n-type ZnSe layer 2 of this embodiment is formed.
Carrier concentration is 1 × 10¹⁷cm^-3Larger than approximately 5 x 1
0¹⁷cm^-3Below, preferably 3 × 10¹⁷cm^-3About 5x
10¹⁷cm^-3Or less, more preferably about 5 × 10¹⁷cm ^-3
Is.

In the above embodiment, the ZnSe blue light emitting diode element in which the n-type ZnSe layer and the p-type ZnSe layer to be the light-emitting layer are formed in this order on the n-type single crystal substrate has been described. In addition, a similar effect can be obtained with a ZnSe blue light emitting diode element in which a p-type ZnSe layer and an n-type ZnSe layer to be a light emitting layer are formed in this order.

Although a GaAs single crystal substrate is used as the substrate in the above description, a zinc blende type single crystal substrate having a lattice constant equal to or close to that of ZnSe and having the same crystal system as ZnSe can be appropriately used. , for example, ZnSe single crystal substrate, In _x Ga _1-x As single crystal substrate, ZnS _x Se _1-x single crystal substrate or the like can be used.

[0024]

In the ZnSe blue light emitting diode element of the present invention, the n-type ZnSe layer serves as a light-emitting layer, and the n-type carrier concentration is larger than 1 × 10 ¹⁷ cm ^{−3 and} is approximately 5 × 10 ¹⁷
Since it is cm ⁻³ or less, the emission intensity is higher than in the past.

In particular, the carrier concentration of the p-type ZnSe layer is set to 1
When × from 10 ¹⁷ cm ^-3 or more and 4 × 10 ¹⁷ cm ^-3 or less, since the hole from the p-type ZnSe layer to the n-type ZnSe layer is efficiently injected, the n-type ZnSe layer is particularly good emission Functions as a layer.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a ZnSe blue light emitting diode element according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between carrier concentration and emission intensity of an n-type ZnSe layer.

FIG. 3 is a diagram showing a relationship between emission intensity and applied current.

[Explanation of symbols]

 1 n-type GaAs single crystal substrate 2 n-type ZnSe layer 3 p-type ZnSe layer

Claims (2)

[Claims] 1. A first-conductivity-type single crystal substrate, a first-conductivity-type ZnSe layer formed on the single-crystal substrate, and a first-conductivity formed on the first-conductivity-type ZnSe layer. ZnS layer having a second conductivity type ZnSe layer having a conductivity type opposite to that of the ZnS layer
In the e light emitting diode element, the ZnSe layer of the first and second conductivity type ZnSe layers having a conductivity type of n-type serves as a light-emitting layer, and the n-type carrier concentration thereof is 1 × 10 ¹⁷ cm 2.
ZnSe blue light emitting diode element characterized in that it is larger than ^{-3 and} is approximately 5 × 10 ¹⁷ cm ^-3 or less. 2. A carrier concentration of a ZnSe layer having a p-type conductivity is 1 ×, among the first and second conductivity type ZnSe layers.
10 ¹⁷ cm ^-3 or more from 4 × 10 ¹⁷ cm ^-3 ZnSe blue light emitting diode element according to claim 1, characterized in that a following.