JPS59172280A - Ii-vi group intermediate compound semiconductor hetero-junction device - Google Patents

Abstract

PURPOSE:To extract beams efficiently by using the forbidden band width of a crystal of specific eV or more as that of a light-emitting region and constituting the titled device by a crystal, the forbidden band width of an adjacent region thereof is wider than that of the light-emitting region and an electric conduction type thereof is reverse to the light-emitting region. CONSTITUTION:A light-emitting region is formed by a P-N junction of the same kind by a II-VI compound of 2.5eV or more, and a semiconductor device of high performance can be shaped by a hetero-junction having structure in which the same conduction type crystal of large forbidden band width is constituted on the outside of the P-N junction. ZnS and ZnSe can be listed up as possible crystals, and mixed crystals acquired by linearly approximating the forbidden band width of each compound are used. Combinations, such as ZnSe-Cd0.35Zn0.65S, (CdZn)Se- (CdZn)(SSe), etc. are considered as ones, in which the light-emitting regions operate at 2.5eV or more and lattice constants coincide, in consideration of lattice constants in the hetero-junction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ■-■ intergroup compound semiconductor device, and particularly to a ■-■ intergroup compound semiconductor device.
-■Relating to an intergroup compound semiconductor heterojunction device.

II-VI intergroup compound semiconductors have direct transition type crystals with a forbidden band 1] or ■-■ intergroup compound semiconductors, which have larger crystals than intergroup compounds.
It has unique properties that cannot be obtained with m-v intermittent compounds, and is particularly promising for the realization of blue light-emitting diodes.

However, in the conventional growth method, this crystal can be grown by ■−■
Unlike intergroup compounds, the electrical conductivity type cannot be controlled to p-type or p-type by adding impurities, and only crystals of electrical conductivity type specific to each crystal can be obtained. This is shown in Table ζ along with other characteristics.

Table 1 Properties of 1I-VI Compounds This relationship is based on the control of high vapor pressure component elements and crystal properties (non-chemical stoichiometric composition). Furthermore, in the case of II-VI intergroup compounds, as shown in the temperature-vapor pressure curves of each constituent element in Figure 1, the vapor pressure of each constituent element is high, and the It is thought that the non-stoichiometric composition of the crystal strongly controls the crystal properties more than the intermediate compounds. That is, for five crystals other than the Cd Te crystal, the vapor pressure values of each constituent element at the same temperature are compared and classified.

If the vapor pressure of group ■ elements is Pn, and the vapor pressure of group ■ elements is P■, then comparing Figure 1 with fi '%■ ■
When the vapor pressure of the group element is higher than that of the group element, that is, Pn >
PVI... As a specific example, in the case of ZnTe, only p-type crystals have been obtained.

On the other hand, if the vapor pressure of the group ■ ■ element is higher than that of the group ■ element, that is, P
n< PV[--ZnS1ZnSe 1Cd 3%Cd
In the case of Se, only n-type crystals have been obtained.

These results were obtained using conventional growth methods that do not take into account the control of the non-stoichiometric composition of the crystal, and in each case defects in high vapor pressure constituent elements strongly influence the conductivity type. It is expected that That is, in the case of (1), the defects in the group (2) element are the main factor determining the electrical conductivity type, and in the case (2), the defects in the group (2) element are the main factor determining the electrical conductivity type.

These characteristics have made possible the application of II-VI compounds. To illustrate this method, a representative II-
This will be specifically explained by taking Zn5e, which is a Vl compound, as an example.

■ When growing p-type crystals, Se, a high vapor pressure component element, is used as a solvent, a temperature difference is created above and below the solvent, and the solute Zn Se is floated on the high temperature side.
A p-type ZnSe crystal can be grown by controlling the vapor pressure of Zn, which is a low vapor pressure component element, and adding group (I) elements such as Cu, Atx, Ag, Li, Na, and K.

Electrical conductivity is determined by the amount of impurity added and the Zn value applied. With the same amount of impurity added, the lowest impurity density is at the Zn pressure value where the deviation from the stoichiometric composition is the smallest, but on the lower Zn pressure side The p-type electrical conductivity is high.

■ When growing an n-type crystal In this case, contrary to (■), an n-type crystal can be obtained by using Zn, a low vapor pressure component element, as a solvent and controlling the vapor pressure of Se, a high vapor pressure component element. It will be done. The impurity is preferably F, (J, Br, etc.) of group (1), and in this case also it is possible to grow an n-type crystal with higher electrical conductivity in the low pressure region of Se.

In this way, by using the vapor pressure controlled temperature difference liquid phase growth method already provided by the present inventor, low resistance p-type and n-type
It became possible to grow shaped crystals, and the field of application of II-VI compound semiconductors was dramatically developed. In the above growth method, it is easily predicted that an epitaxially grown layer can be obtained at a constant temperature by inserting the substrate crystal on the low temperature side of the solvent.

The semiconductor device of the present invention will be described below. A high-efficiency blue light-emitting device is provided in the compound ■-■, and the forbidden phase of the light-emitting region is a crystal with 2.5 eV or more, and the adjacent region of this crystal is higher than the forbidden phase of the light-emitting region. l] is wide < (Eg >2.5 eV) and is composed of crystals with opposite electrical conductivity types.
This is a T-VI compound semiconductor heterojunction device. With this structure, carriers are easily injected from the wide crystal in the forbidden phase, and are efficiently recombined in the light emitting region.
and the same type of p-n due to something that does not absorb the emitted light
It goes without saying that a semiconductor device with even higher performance can be formed by forming a heterojunction with a structure in which a large conduction wheel crystal in a forbidden phase is formed on the outside of the heterojunction.

From the table, ZnS and ZnSe can be restored as crystals that can be used to construct this semiconductor device, and as shown in Figure 2, the mixed crystal obtained by linear approximation in the forbidden phase of each compound is (Zn5e) x (
ZnS) 1-x.

(ZnS)x (CdS) l-x, (ZnSe)
x (ZnTe)+-x and (ZnSe) x
(Cd5e)t-x.

Zn+ -x Cd x S+ -y Sey, Z
The target crystal group is nt −x Cd x Se+ −yTey.

By mutually combining these, the semiconductor device of the present invention is constructed.

For example, Zn5(p)-ZnSe(n), Zn5
l-xSex (p) -Zn Se (n), Zn 5
e(pl −Zn+−x Cd, c S+ −ySey
There are several dozen combinations such as (n).

For example, when comparing the brightness at the same emission wavelength in the case of a heterojunction and a homojunction in which the light emitting region is ZnSe, the brightness in the case of the heterojunction is approximately twice, and it is clear that the characteristics have been improved. be. It has also been found that, although the improvement rate is not high, better characteristics can be obtained when the light emitting region is made n-type than when it is made p-type.

Next, in order to consider the lattice constant between heterojunctions, the lattice constants of typical II-VI compounds are shown in FIG. In this case as well, according to Vegard's law, the lattice constant of the mixed crystal can be determined by linear interpolation of lattice constant values between compounds. Furthermore, in order to realize the above-described heterojunction and to consider lattice constant matching, FIG. 4 shows the relationship between the forbidden phase and the lattice constant. As is clear from the figure, there are only a few combinations in which the emission region is 2.5 eV or higher and the lattice constants match (for example, Zn Se -Cdo, +s Zno, 6s 5 (Cd
Zn) Se - (Cd Zn) (S 5e) (C
d Zn) Se −Zn (Se Te) (Cd
Possible combinations include Zn)Se-(CdZn)S. (However, the former is the light emitting region.) Therefore, from the viewpoint of operating life, operating efficiency, etc., it is possible to realize a good heterojunction between the crystals corresponding to the shaded region in FIG. 4.

Furthermore, in order to increase the luminous efficiency in the light emitting region, it goes without saying that the crystals in the region adjacent to the light emitting region can be reduced.

In this case, the indirect transition type crystal is, for example, SiC.

[Brief explanation of the drawing]

Figure 1 is a graph showing the vapor pressure of each element, Figure 2 is the forbidden phase of a mixed crystal that can emit blue light, Figure 3 is the lattice constant of l crystal that can emit blue light, and Figure 4 is the lattice constant. This is Class 7, which shows the relationship between prohibition and prohibition. Patent applicant (11) 392-

Claims (3)

[Claims] (1) The forbidden band width of the crystal constituting the light emitting region is 2.5 eV
and at least one implantation region adjacent to the light-emitting region is composed of a forbidden band l] or a crystal larger than the light-emitting region and having an opposite electrical conductivity type. Awesome compound semiconductor heterojunction. (2) The forbidden band l] of the light emitting region is larger than 2.5 eV, and is composed of a P-〇 junction made of at least one identical crystal, and the regions adjacent to both sides of this junction have the same electric potential as the light emitting region. ■-■ Intergroup compound semiconductor heterojunction device (■) characterized by comprising a crystal that is conductive and larger than the forbidden band 11 or the light-emitting region. (3) At least one of the regions adjacent to the light emitting region is a device.