JPH04245211A - Optical evaluation device - Google Patents

Abstract

PURPOSE:To provide an optical evaluation device to easily perform high sensitivity sensing of the impurity level using Zeeman splitting or sensing of Landau level by holding a specimen at an ultra-low temperature and in a ferro-magnetic field over one tesla in a device to measure the photo-luminescence from a micro- part using an optical microscope system. CONSTITUTION:In an optical evaluation device, a specimen 7 placed in a specimen cryostat is irradiated with a laser beam via an objective lens 1 of microscope and a glass window 6 mounted in the lid 5 of the cryostat 4, and the light emitted from the specimen 7 is introduced into the barrel 8 of the microscope through the glass window 6 and objective lens 1, and further into a sensor for measurement of the photo-luminescence. This enables measuring at an ultra- low temp. and in ferro-magnetic field on the accasion to measure the optical characteristics such as photo-luminescence using an optical microscope system.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an apparatus for measuring luminescence from minute parts using an optical microscope system, in which a sample is kept at an extremely low temperature and in a strong magnetic field of 1 Tesla or more, and high sensitivity is achieved using Zeeman separation. The present invention relates to an optical evaluation device for easily detecting impurity levels or Landau levels.

0002

[Prior art] Conventionally, photoluminescence measurement at ultra-low temperatures of 10K or less using an optical microscope system for measuring light emission from a minute area, and high sensitivity using Zeeman separation from samples such as semiconductors in a relatively wide area. Photoluminescence measurements at extremely low temperatures of 1 Tesla or higher for detecting impurity levels or Landau levels have been performed separately. However, luminescence measurements using an optical microscope system that combines both measurements under a strong magnetic field of 1 Tesla or more and at an extremely low temperature of 10 K or less have not been carried out mainly due to difficulties in the equipment configuration.

A conventional cryostat compatible with an optical microscope system has a reservoir of liquid helium as a main coolant and liquid nitrogen as an auxiliary coolant surrounding it, and cools the sample by heat conduction to the reservoir of liquid helium, which is the main coolant. The method is based on Therefore, the shape is large and heavy, and it is difficult to make the main part of the sample cryostat into which the sample is placed into a long cylindrical shape. Therefore, when trying to apply this device to the present device, it is difficult to insert the sample cryostat into the coil of the superconducting magnet. Moreover, even if it were possible to do so, it would be difficult to move freely in the axial direction of the coil, and the heavy superconducting coil would obstruct it, making it laborious to replace the sample. Furthermore, there were other problems such as difficulty in measuring the luminescence distribution by moving the cryostat.

0004

[Problems to be Solved by the Invention] It is an object of the present invention to provide a method for measuring optical properties such as luminescence using an optical microscope system at extremely low temperatures and in a strong magnetic field of 1 Tesla or more, and to provide an easy method after measurement. An object of the present invention is to provide an optical evaluation device having a compact and lightweight cryostat for a sample to be inserted into a superconducting coil that allows sample exchange.

[0005]

[Means for Solving the Problems] The present invention provides a method for preparing samples at 10K.
The cryostat that maintains the temperature below is a liquid helium flow type cooling system that can be compactly inserted into the superconducting coil. In addition, by making the sample cryostat into a cylindrical shape that can be moved freely in the axial direction of the coil within the superconducting coil, the cryostat can be moved around the coil when replacing the sample attached to the tip of the cryostat after measuring luminescence at the center of the coil. The sample can be easily replaced by moving it in the direction of deep insertion in the axial direction or by pulling it out from the coil.

[0006]

[Examples] The present invention will be explained below with reference to Examples.

FIG. 1 shows an embodiment of an optical evaluation device according to the present invention, which shows an objective lens 1 of a microscope and a superconducting coil 2 in a device that measures luminescence in a strong magnetic field using an optical microscope system. FIG. 2 is a schematic diagram of an optical evaluation apparatus having a coil cooling cryostat 3 and a sample cryostat 4.

The above-mentioned optical evaluation device includes a microscope objective lens 1
, the sample 7 inside the cryostat is focused and irradiated with laser light through the glass window 6 attached to the lid 5 of the sample cryostat 4, and the emitted light from the sample 7 is transmitted through the glass window 6,
This is an optical evaluation device that measures photoluminescence by introducing light into a microscope barrel 8 through an objective lens 1 and further introducing the light into a detector.

[0009] In the above optical evaluation device, the superconducting coil 2
The magnetic field in the core is 5 Tesla, and the superconducting coil 2 is relatively compact in order to move it horizontally on the XY horizontal drive stage 9 together with the sample cryostat to control the laser irradiation position on the sample 7. The core diameter is also small. In this embodiment, the diameter of the hole 10 in the core of the coil cryostat 3 is about 4 cm. Insert the main body cylindrical part 11 of the sample cryostat 4 into this hole 10 so that the sample position is at the axial center position of the coil.
Insert it approximately m (in the state shown in Figure 1) and measure the luminescence. When replacing the sample after measurement, raise the objective lens 1 and take it out of the hole 10, and insert the main body cylindrical part 11 into the hole 10.
0 deeply (about 20 cm) so that the position of the upper lid 5 is at the same height as the top of the hole 10 of the coil cryostat 3, then loosen the screw 12 that closes the lid 5, and then close the lid 5. It is designed so that it can be removed and the sample 7 replaced. As a result, samples can be easily replaced without lifting and moving the coil cooling cryostat 3 having the compact but heavy coil 2, liquid helium reservoir 13, and liquid nitrogen reservoir 14 from the support base 15.

[0010] A cryostat for specimens in which the main body cylindrical part 11 has an outer diameter of approximately 4 cm, a length of 20 cm or more, and the specimen 7 is located at the tip of the cryostat as in this embodiment is compatible with conventional optical microscope systems. A sample cryostat, which has a reservoir of liquid helium as the main coolant and liquid nitrogen as an auxiliary coolant surrounding it, cools the sample by heat conduction to the reservoir of liquid helium, the main coolant.
The shape including the outer diameter is large and difficult to realize, and it can only be easily realized by a flow type having a capillary tube 16 for liquid helium flow shown in FIG.

[0011] Furthermore, this type of cryostat for liquid helium flow is light in weight, making it easy to move up and down 17 when taking out a sample, and furthermore, there is no burden on the motor when driving XY horizontally.

In this embodiment, when taking out the sample, the main body cylindrical part 11 of the sample cryostat 4 was inserted deeply (into the top in FIG. 1) into the hole 10 of the coil cryostat 3; Cylindrical part 1
1 to the insertion length required for luminescence measurement, pull it out from the hole 10 (lower in Figure 1), and attach the sample cryostat 4 to the coil cooling cryostat 3.
You can also take it out from underneath and replace the sample.

[0013]Also, although this embodiment was a photoluminescence method in which luminescence is extracted by irradiating a laser beam,
Electroluminescence can be performed in a strong magnetic field by pulling out lead wires from the sample, applying an electric field, and extracting the luminescence from the objective lens.

[0014]

[Effects of the Invention] As explained above, the present invention uses a liquid helium flow type cooling system as a cryostat for keeping a sample at a temperature of 10 K or less, and has a configuration that can be compactly inserted into a superconducting coil. Therefore, when measuring optical properties such as luminescence using an optical microscope system, measurement at extremely low temperatures and in a strong magnetic field can be realized.

In addition, since the cryostat has a cylindrical shape that can be moved freely in the axial direction of the coil within the superconducting coil, when replacing the sample after measuring luminescence at the center of the coil, the cryostat for the sample can be moved freely in the axial direction of the coil. Allows movement in the axial direction. Therefore, operations such as deeply inserting or pulling out the sample cryostat become easy, and thereby it becomes easy to take out the sample attached to the tip.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an optical evaluation device according to the present invention.

[Explanation of symbols]

2 Superconducting coil 3 Cryostat for coil cooling 4 Cryostat for samples 7 Sample 8 Microscope barrel

Claims (3)

[Claims] Claim 1: In an apparatus for measuring optical properties such as luminescence using an optical microscope system, a sample is
An optical evaluation device that has a cryostat for maintaining the temperature below K, a superconducting coil for applying a strong magnetic field of 1 Tesla or more to the sample from around the cryostat, and a cryostat for cooling the superconducting coil. . 2. The optical evaluation apparatus according to claim 1, wherein the cryostat for maintaining the sample at a temperature of 10 K or less is a refrigerant flow type cooling system such as liquid helium. 3. The optical evaluation device according to claim 2, wherein the cryostat for maintaining the sample at a temperature of 10 K or less has a cylindrical shape that can be freely moved in the axial direction of the superconducting coil.