An opto-electronic device with the physical and chemical characteristics at the junction thereof being well matched is disclosed. The opto-etectronic device includes a wafer, a first layer grown on the wafer, and a second layer grown on the first layer, wherein one of the first and second layers is an ordered structure while the other is a disordered structure.

BACKGROUND OF THE INVENTION 
The present invention relates generally to an opto-electronic device, and 
more particularly to an opto-electronic device with a junction. 
Although the characteristics of the opto-electronic device with a junction 
have been improved significantly due to the design of the heterojunction, 
it still has a bottleneck, i.e., if there is a slight mismatching of the 
physical or chemical characteristics at the junction, the resulting device 
will have defects, which will inevitably cause deterioration of the 
characteristics thereof. Such defects may be reduced or alleviated by 
strictly controlling the heterojunction material system and the selection 
of the growth conditions, but such control is not only costly, but also is 
not always satisfactory. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an 
opto-electronic device having a good junction characteristic. 
Another object of the present invention is to provide an opto-electronic 
device, the growth system and procedures which are simple, and need not 
consider the memory effect of the system. 
The basic technical concept of the present invention utilizes the practical 
principle that there is a different energy gap between the ordered and 
disordered structures, the junction of which is treated as a 
hetero-equivalent junction. The experiment demonstrated that the 
semiconductor device manufactured in accordance with this principle is 
improved in its characteristics, such as an increased luminescence 
intensity as well as the increased linear region of the luminescence 
intensity current diagram. Furthermore, the growth system therefore is 
simple, and does not need to consider the memory effect of the system. 
Moreover, since the heterojunction is made of the same material, its 
physical and chemical characteristics are self-matching and excellent, and 
the problem of the constituent mutual diffusion will not occur at the 
junction. 
Utilizing the Ga.sub.0.5 In.sub.0.5 P as an example, the ordered/disordered 
structures described above mean that if the Ga and In atoms are arranged 
at random on the sublattice, it is called a disordered structure. On the 
contrary, if the Ga and In atoms are arranged on the (111) lattice plane 
in the order of Ga-P-In-P, it is called an ordered structure. 
In accordance with the present invention, an opto-electronic device 
includes a wafer, an ordered (disordered) first layer grown on the wafer, 
and a disordered (ordered) second layer grown on the first layer. 
Providing an ordered (disordered) third layer grown on the second layer 
can produce a better effect. The so-called opto-electronic device may be a 
light emitting diode (LED), a laser diode, or a high speed device. Of 
course, the wafer as well as the second or third layer should be provided 
with ohmic contacts in practical applications. 
The materials for the layers may be a metal and a compound capable of 
providing phosphorus. The so-called metal, if being an organic metal, may 
be organometallic gallium or indium. The compound capable of providing 
phosphorus may be a gas, such as PH.sub.3. The p-type dopant may be a 
Group II metal, and the n-type dopant may be a compound having s Group IV 
or VI element. Furthermore, the wafer of the present invention may be 
constituted by the GaAs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to a preferred embodiment of the present invention, an 
opto-electronic device includes a wafer, an ordered (disordered) first 
layer grown on the wafer, a disordered (ordered) second layer grown on the 
first layer, an ordered (disordered) third layer grown on the second 
layer, and two ohmic contacts provided on the wafer and the third layer 
respectively by means of a vacuum evaporation process. The manufacturing 
process for a red light emitting diode, which is grown on a GaAs wafer and 
has double heterojunctions, in accordance with the present invention, will 
be hereinafter described in detail, particularly with reference to FIG. 1. 
First, a (100) 2.degree. of [110] n.sup.+ -GaAs substrate having a 
concentration of 7.3.times. 10.sup.18 cm.sup.-3, an etch pit density (EPD) 
of 5.times.10.sup.3 cm.sup.2, and a thickness of 350 .mu.m undergoes an 
epitaxy growth of the Ga.sub.0.5 In.sub.0.5 P in a metal organic chemical 
vapor deposition (MOCVD) system. (C.sub.2 H.sub.5).sub.3 Ga maintained at 
5.degree. C., (CH.sub.3).sub.3 In retained at -5.degree. C. and PH.sub.3 
being 5% in H.sub.2 are utilized as the growing materials for Ga, In, and 
P, respectively. In addition, SiH.sub.4 being 500 ppm in H.sub.2 and 
(C.sub.2 H.sub.5).sub.2 Zn are utilized as the materials for the n-type 
dopant Si and p-type dopant Zn, respectively. The system is then heated by 
the high frequency wave, and the epitaxy is grown within a reaction tube 
having a diameter of 4.5 cm under a low pressure (100 Torr). The 
above-mentioned materials can all be bought from the Morton Company in the 
United States of America. 
During growth, as shown in FIG. 2, a Si-doped n-type disordered Ga.sub.0.5 
In.sub.0.5 P layer is firstly grown as a lower confinement layer having a 
concentration of 3.times.10.sup.17 cm.sup.-3 at 730.degree. C. An undoped 
and ordered active layer having a background concentration of 
2.times.10.sup.16 cm.sup.-3 is then grown at 675.degree. C. A high 
Zn-doped and disordered p-type upper confinement layer having a 
concentration of 3.times.10.sup.18 cm.sup.-3 is further grown at 675 
.degree. C. 
Finally, after the ohmic contacts go through the vacuum evaporation process 
provided therewith, the light emitting diode with double heterojunction is 
completed. The relative energy gaps for such a diode are shown in FIG. 3. 
Since the ordered and disordered structures have different energy gaps and 
the photoluminescence is a good testing medium for the energy gaps. An 
experiment was conducted which shows the test results in FIG. 4, from 
which it can be clearly seen that the energy gap of the disordered 
structure is 2.014 eV while the energy gap of the ordered structure is 
1.928 eV (with another Zn energy level at 1.984 eV). The energy gap 
difference of 86 meV is determined by the test conducted at 77 .degree. K. 
If the test is executed at room temperature (300.degree. K.), the energy 
gap difference will be 70 meV. 
As shown in FIG. 5, the luminescence intensity of the present invention can 
be increased seven times if compared with the general Ga.sub.0.5 
In.sub.0.5 P light emitting diode with the homojunction. 
In summary, the advantages of the present invention can be listed briefly 
as follows: 
1. The characteristics of the resulting semiconductor device are 
significantly improved to successfully simulate that the device has a 
heterojunction; 
2.The growth system for the present invention is simple, and does not need 
to consider the memory effect thereof; 
3. The physical and chemical characteristics at the heterojunction can be 
self-matched, and the junction properties are excellent; 
4. The problem of the constituent mutual diffusion will not occur at the 
junction; 
5. The principle of the present invention can be applied to all of the 
disordered/ordered material systems; and 
6. The growing process for the present invention is simple and easily 
controllable. 
While the invention has been described in terms of what is presently 
considered to be the most practical and preferred embodiment, it is to be 
understood that the invention is not limited to the disclosed embodiment. 
On the contrary, it is intended to cover various modifications and similar 
arrangements included within the spirit and scope of the appended claims, 
the scope of which should be accorded the broadest interpretation so as to 
encompass all such modifications and similar structures.