JPH0748670Y2 - Molecular beam cell - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to the structure of a molecular beam cell used in the molecular beam epitaxial growth method (MBE). In particular, it relates to improvement of the bonding structure between the reflector and the base of the molecular beam cell.

[Prior art]

The structure of a conventional molecular beam cell will be described with reference to FIG. The crucible 1 is a bottomed cylindrical container. It contains the source material. The heater 2 is a resistance heater and heats the raw material. The thermocouple 3 contacts the bottom of the crucible 1 and monitors the temperature. A concentric cylindrical reflector 4 is provided on the outer periphery of the heater 2, and a thin disc-shaped reflector 5 is provided below the heater 2. The base 5 is a disk-shaped thick plate, on which the disk-shaped reflecting plate 10 is stacked, and the cylindrical reflecting plate 4 is fixed thereto. Since the present invention relates to fixing the cylindrical reflector 4 and the base,
This part will be described. There are a plurality of concentric reflectors. Since these have small protrusions on the punch,
When combined concentrically, there will be suitable voids between each other. Moreover, since the plurality of reflectors are in contact with each other by the protrusions, the integrity can be maintained. Therefore, if the outermost reflector is fixed to the base, the entire reflector and the base can be fixed. Conventionally, some small claws 6 are formed on the lower end of the outermost (outermost) reflection plate, and the claws 6 are bent 90 ° to press the lower surface of the base 5. Even when the crucible 1 is fixed to the reflection plate 4, the claw 7 is formed on the upper end of the reflection plate 4 and can be folded. When fixing the crucible, it may be pressed with a ring-shaped cap. Besides, there is a fixing structure as shown in FIG. This is one in which a screw hole is formed in the base, a screw hole is formed in the reflection plate 4, and the screw is fixed by a screw 17. The base can be threaded with metal such as Mo. The screws can also be made of metal such as Ta.

[Problems to be solved by the device]

If the components of the molecular beam cell, such as the heater, the reflector, and the crucible, are consumed and malfunction, they must be replaced. Therefore, the reflector 4 is removed from the base 5.
This is done by extending the nail 6 and pulling out the base 5. When the compensation is completed, the base 5 is again inserted into the outermost peripheral plate of the reflection plate 4 and the claw 6 is bent. High-purity Ta is usually used because the reflector has to withstand high heat and can be processed into a thin plate. The Ta reflector is highly flexible, but it will eventually break if repeatedly bent. Then the reflector itself must be replaced. As described above, the fixing by the bending claw has a drawback that it cannot withstand long-term use. Further, the method of fixing the screw in the screw hole has the following drawbacks. When the temperature of the molecular beam cell is raised, the temperature of the base also rises and the screws stick to the screw holes in the base. Therefore, even if you try to remove the screw, it will not turn. If you try to force it, the screw will break. The conventional fixing mechanism has the above-mentioned drawbacks. SUMMARY OF THE INVENTION It is an object of the present invention to overcome these difficulties and provide a fixing mechanism that can be repeatedly used, a combination of a reflector and a base, and that can be easily removed.

[Means for Solving the Problems]

In the molecular beam cell of the present invention, a cutout groove including a hypotenuse is provided at least in part at the lower end of the outermost peripheral cylindrical reflector. Pins are provided on the outer circumference of the base. Then, the reflection plate is fixed to the base by screwing the pin of the base into the cut groove of the reflection plate. Since it is a cut groove having a hypotenuse in part, when the pin is inserted into the cut groove and screwed in, the pin does not come off from the cut groove due to the action of the hypotenuse. Two or more pins are provided on the base. 3-4 pieces are desirable.
The same number of cut grooves as pins are required. The distribution of the pin and the groove to be cut is equal. For example, assume that four pins are attached to the base. It is not necessary to install every 90 °, but there must be four notches so that the distribution of these is equal to the distribution of pins. The notch must be continuous from the bottom edge of the reflector. If the notch groove extends only in the axial direction, the base easily comes off. Therefore, a cut groove including at least a part of the oblique side is formed.

[Action]

Insert the outermost one of the reflectors to the outside of the base and turn it so that the pins enter the groove. Then turn the reflector slightly so that the pin enters the hypotenuse of the groove. Then, the reflector will not come off from the base unless the base rotates relative to the reflector. While the molecular beam crystal is growing, the molecular beam cell is heated, but since it is the pin and the groove, the contact area is small, and both do not stick to each other and stick. If the molecular beam cell needs to be repaired, take the molecular beam cell out and twist the base backwards. Then, the base comes off the reflector. After repairing, it is easy to attach the base to the reflector. When removing or installing the base, the claws do not bend, so there is no fatigue on any part. It does not deform or break even if it is attached and removed many times, so it can withstand repeated use.

【Example】

The structure of a molecular beam cell according to an embodiment of the present invention will be described with reference to FIG. This shows an example in which there are two upper and lower bases. Positioning of the reflector becomes more accurate because there are two on the top and bottom. Of course, the present invention can be applied even if the base is one. The crucible 1 is a container for accommodating a raw material and has a cylindrical shape with a bottom and a flange portion at the opening. This is made of a heat resistant insulator such as PBN. The heater 2 is installed around the crucible 1 and heats the raw material. This may be a heater wound in a coil or a ribbon heater meandering up and down. Here, a coil heater is shown as an example. A concentric cylindrical reflector plate 4 is provided on the outer periphery of the crucible 1 and the heater 2. Below the crucible 1 is a disc-shaped reflector.
10 are stacked. These are Ta as already mentioned
Although it is made of a thin plate, a protrusion is formed by a punch, so that an appropriate gap is formed between the adjacent reflectors. The reflectors 4 and 10 reflect the heat generated by the heater 2 and the crucible 1
It returns it to the raw material in. The thermocouple 3 monitors the temperature of the lower bottom of the crucible 1. Below the crucible 1 and the heater 2, there are a base 9 and a base 5. The upper base 9 and the lower base 5 are connected to each other by Mo struts 12. Only the outermost circumference of the cylindrical reflector 4 extends downward and surrounds the upper base 9, the pillar 12, and the lower base 5. The structure above the upper base 9 has the same structure as the conventional molecular beam cell. The brim portion of the crucible 1 is fixed by bending a claw formed on the upper end of the outermost reflection plate, or by inserting a separate annular cap. The structure having the upper and lower bases is provided so that the axis of the base and the axis of the reflector are precisely aligned. A plurality of pins 8 are projectingly provided on the outer circumference of the lower base 5.
Corresponding to this, a cut groove 11 is cut at the lower end of the outermost peripheral plate of the reflection plate 4. This is a groove that extends upward from the lower end and then obliquely to the right. The groove to be cut must be partially angled. The base 5 and the reflection plate 4 can be coupled by screwing the pin 8 into the groove 11 for cutting. The base 5 can be removed by turning it in the opposite direction. However, the base 5 does not come off naturally. Two or more pins 8 and cut grooves 11, 3, 4, 5, 6, ...
· · Any number of In the example of FIG. 1, the depth of the connection between the base and the reflection plate changes depending on the screwing angle. If this is not desirable, the end portion of the cut groove 11 may be a horizontal groove. This is shown in FIG. This will keep the bond depth of the base constant. FIG. 2 shows another embodiment. This shows only the joint between the base and the reflector. A flange 13 having a large diameter is formed by the lower end of the base. With this arrangement, when the base 5 is screwed in, the collar portion 13 abuts on the lower end of the reflection plate, so that the coupling depth of the base is determined. This is more accurate because the positioning of the base and the reflector is done by the horizontal plane.

[Effect of device]

In the present invention, the reflection plate of the molecular beam cell and the base are connected by a pin protruding from the base and a groove formed in the reflection plate. Do not bend or deform a part of the reflector at the time of joining and separating. For this reason, even if it is repeatedly coupled and separated, a part of the reflection plate will not be broken. Further, the pin and the cut groove will not be seized even if the heat becomes high. Therefore, removal is always possible. As described above, the coupling structure of the present invention has excellent durability.
In addition, disassembly and assembly are easy, and maintainability is good.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a molecular beam cell according to an embodiment of the present invention. FIG. 2 is a partially longitudinal front view of a base of a molecular beam cell and a connecting portion of a reflector according to another embodiment of the present invention. FIG. 3 is a vertical sectional view of a molecular beam cell according to a conventional example. FIG. 4 is a vertical sectional view of only a base and a reflector of a molecular beam cell according to another conventional example. FIG. 5 is a front view of the vicinity of the base of a molecular beam cell showing another embodiment of the present invention. 1 …… crucible 2 …… heater 3 …… thermocouple 4 …… reflector 5 …… base 6,7 …… claws 8 …… pin 9 …… bottom base 10 …… reflector 11 …… cut groove 12 …… Prop 13 …… Bill 17 …… Screw

Claims (1)

[Scope of utility model registration request] 1. A crucible for containing a raw material, a heater provided around the crucible for heating the raw material, a plurality of concentric cylindrical thin plate reflectors provided around the heater, and below the crucible and the heater. In a molecular beam cell composed of a plurality of thin disk-shaped reflecting plates provided in, and a disk-shaped base that supports the cylindrical reflecting plate and the disk-shaped reflecting plate, the outermost periphery of the cylindrical reflecting plate A cut groove including a hypotenuse at least in part is provided at the lower end of the object, a pin is provided on the outer periphery of the base, and the reflector plate is fixed to the base by screwing the pin of the base into the cut groove of the reflector plate. Molecular beam cell.