JP2671791B2 - Molecular beam source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to molecular beam crystal growth (MB).
E) The structure of the molecular beam source used in the device.

[0002]

2. Description of the Related Art In the Knudsen cell widely used as a conventional molecular beam source, in order to control the molecular beam intensity,
I was changing the heating temperature. By this method, gallium (G
Stable molecular beams of Group 3 elements such as a) have been obtained. Further, as a method of controlling the molecular beam intensity, a method of changing the opening area of the shutter (Japanese Patent Laid-Open No. 61-174194) and a method of using a needle valve at the outlet of the crucible have been tried.

[0003]

However, in the method of controlling the heating temperature, arsenic (As) and selenium (Se) are used.
Materials having a high vapor pressure such as sublimate have a problem that the molecular beam intensity cannot be changed in a short time because it takes a long time of about 1 hour to stabilize the temperature. The method using a shutter has a problem that the material adheres to the shutter and falls into the crucible, or the opening is clogged. Further, in the method using a needle valve, a metal must be used for the valve, which has a problem that it reacts with a molecular beam material and is easily broken due to the pressure applied to the valve. The purpose of the present invention is to control the molecular beam intensity in a short time,
It is to provide a molecular beam source that is stable and does not break easily in a vacuum.

[0004]

A molecular beam source according to the present invention has a material chamber for holding a molecular beam material, an evaporation hole provided in the material chamber, and a control section adjacent to the evaporation hole. A motion introducing device for driving the control unit, a heater for heating the material chamber, the evaporation hole, and the control unit, and driving the control unit by the motion introducing device from outside the vacuum, It is characterized in that the emission cross-sectional area of the molecular beam is changed and the molecular beam intensity is controlled by changing the overlapping area with the control unit.

[0005]

Since the control section is driven from outside the vacuum to change the emission cross section of the molecular beam, the intensity of the molecular beam can be changed within a few seconds. Since the evaporation hole and the control unit are inside the crucible and are heated, the molecular beam material does not adhere and the evaporation hole is not clogged. Since the overlapping area of the evaporation hole and the control unit is changed, no pressure is applied to the evaporation hole. Therefore, it is hard to break down, and a material other than metal such as pyrolytic boron nitride (PBN) can be used as a material. Further, since the structure is simple, it is easy to manufacture.

[0006]

【Example】

(Embodiment 1) The present invention will be described with reference to the drawings.
1A and 1B are a cross-sectional view and a plan view showing an embodiment of the present invention, and FIG. 2 is a view showing a change in molecular beam intensity.

In the crucible 1, there are a material chamber 3 having an evaporation hole 2 and a plate-shaped control section 4 adjacent to the evaporation hole 2, and the material chamber 3 is filled with arsenic (As) 5 which is a molecular beam material. Has been done. Surrounding the crucible 1 are a heater 6 and a heat shield plate 7, which are fixed to a vacuum flange 9 by columns 8. The temperature of the crucible 1 is measured by the thermocouple 10. Rotary motion introducer 11 attached to vacuum flange 9
Are connected to the control unit 4 via the shaft 12.
Crucible 1, material chamber 3, control unit 4, and shaft are PB
Consisting of N, there is little degassing even when heated. Heater 6
As a result, the arsenic 5 is kept at a specific temperature, and the crucible 1, the material chamber 3, the control unit 4, and the shaft 12 are also heated. By driving the motion introducing device 11 outside the vacuum, the control unit 4 rotates and the rotation angle t changes. The overlapping area of the evaporation hole 2 and the control unit 4 changes according to the rotation angle t, and the emission cross-sectional area of the arsenic molecular beam changes. The arsenic molecular beam intensity is proportional to the emission cross section, and the relationship between the rotation angle t and the arsenic molecular beam intensity is as shown in FIG. The molecular beam intensity is changed from 1.0 to 0.05 by changing the rotation angle t from 0 degree to 90 degree.
It was possible to control with good reproducibility. Further, the time required to change the molecular beam intensity from 1.0 to 0.5 is 30 seconds, which is 1/40 of the time required to control the molecular beam intensity by changing the temperature of arsenic 5. Could be controlled in time. Since the control unit 4 does not completely seal the evaporation holes 2, the molecular beam intensity does not become 0 even when the rotation angle t is 90 degrees, but the molecular beam intensity range required for crystal growth is 1. 0 to 0.1 was sufficient and there was no problem. Rather, the motion of the controller 4 is a rotary motion, and the evaporation hole 2
Since no pressure is applied between the upper surface of the material chamber 3 and the upper surface of the material chamber 3, it is hard to break down, and the reliability, which is the biggest problem in the vacuum apparatus, can be increased.

(Embodiment 2) FIGS. 3 (a) and 3 (b) are a sectional view and a plan view showing an embodiment of the present invention, and FIG. 4 is a view showing a change in molecular beam intensity.

The structure of the evaporation hole, the control unit and the motion introducing device described in the first embodiment is changed. A slit-shaped evaporation hole 2 is provided on the side surface of the material chamber 3, and a columnar control unit 4 is adjacent to the evaporation hole 2. A linear motion introducer 11 attached to the vacuum flange 9 is connected to the control unit 4 via a shaft 12. The material chamber 3, the control unit 4, and the shaft are made of PBN, and degassing is small even when heated. Arsenic 5 is kept at a specific temperature by heater 6, and crucible 1, material chamber 3, control unit 4, shaft 12
Is also heated. By driving the motion introducing device 11 outside the vacuum, the control unit 4 moves linearly. Position s of control unit 4
Corresponding to, the overlapping area of the evaporation hole 2 and the control unit 4 changes, and the emission cross-sectional area of the arsenic molecular beam changes. The arsenic molecular beam intensity is proportional to the emission cross-sectional area, and the relationship between the position s of the control unit 4 and the arsenic molecular beam intensity is as shown in FIG. Control unit 4
By changing the position s of from 0 mm to 10 mm,
The molecular beam intensity could be controlled from 1.0 to 0.01 with good reproducibility. Also, the molecular beam intensity is 1.0 to 0.5.
It takes 30 seconds to change to 5 arsenic
It was possible to control the intensity of the molecular beam by changing the temperature of 1 to 40 times of the time required to control the molecular beam intensity.

Since the control unit 4 does not completely seal the evaporation hole 2, the molecular beam intensity does not become 0 even if the position s of the control unit 4 is set to 0, but the molecular beam required for crystal growth is not. The strength range of 1.0 to 0.1 was sufficient, and there was no problem. Rather, since the pressure on the side surface of the material chamber 3 due to the movement of the control unit 4 is not applied, it is less likely to break down as compared with a needle valve or the like, and the reliability, which is the greatest problem in a vacuum device, can be increased.

[0011]

As described above, according to the present invention, the molecular beam intensity of arsenic, selenium, etc. can be controlled in a short time, and a mixed crystal or heterostructure containing these materials can be grown.

[Brief description of the drawings]

1A is a cross-sectional view showing an embodiment, and FIG. 1B is a plan view.

FIG. 2 is a diagram showing a change in molecular beam intensity.

3A is a sectional view showing an embodiment, and FIG. 3B is a plan view.

FIG. 4 is a diagram showing changes in molecular beam intensity.

[Explanation of symbols]

 1 crucible 2 evaporation hole 3 material chamber 4 control unit 5 arsenic 6 heater 7 heat shield plate 8 column 9 vacuum flange 10 thermocouple 11 motion introducer 12 shaft

Claims (1)

(57) [Claims] 1. In a molecular beam crystal growth (MBE) apparatus, a material chamber for holding a molecular beam material, an evaporation hole provided in the material chamber, and a control unit adjacent to the evaporation hole are provided in a crucible. Having a motion introducing device for driving the control part, and a heater for heating the material chamber, the evaporation hole and the control part, and rotating the control part by the motion introducing device from outside the vacuum to evaporate the material. A molecular beam source characterized in that the emission cross-sectional area of the molecular beam is changed by changing the overlapping area of the hole and the control unit to control the molecular beam intensity.