JP2015028463A - Thermal stimulation current measuring device, thermal stimulation current measuring program, and thermal stimulation current measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a measurement condition suitable for a sample as measuring object easily and quickly, and to perform an appropriate TSC measurement according to the obtained measurement condition.SOLUTION: A thermal stimulation current measuring device for performing thermal stimulation current measurement to a sample 11 as measuring object includes: condition extraction means 45 for obtaining a measurement condition required for performing thermal stimulation current measurement to the sample 11; condition registration means 46 for registering the measurement condition obtained by the condition extraction means 45 in a predetermined data storage area 44; and measurement performing means 41 for performing thermal stimulation current measurement to the sample 11 while using the measurement condition registered in the data storage area 44 by the condition registration means 46.

Description

  The present invention relates to a thermally stimulated current measuring apparatus, a thermally stimulated current measuring program, and a thermally stimulated current measuring method used when performing thermally stimulated current measurement.

  Thermally stimulated current (TSC) measurement causes polarization and charge trapping inside the sample by applying an electric field to the sample, and mainly detects the current generated by the depolarization and detrapping phenomena during the heating process. (For example, refer nonpatent literature 1). According to the TSC measurement, various relaxation phenomena and dispersibility can be evaluated including, for example, a minute glass transition of a polymer material, and electrical characteristics such as charging, dielectric, and insulation can be measured. Further, for example, the detrapping current after photoexcitation can be measured by an irradiation system such as an ultraviolet to infrared region or a laser beam. From the above, for TSC measurement, various types of samples such as polymer materials, toners, pharmaceuticals, and organic / inorganic semiconductors can be measured.

Japan Society for the Promotion of Science, Organic Materials for Information Science, 142nd Committee, Section C, “Organic Semiconductor Devices—From Basics to Advanced Materials and Devices”, Ohmsha, October 2010, p. 429-449

  By the way, in order to appropriately perform TSC measurement in which various samples can be measured, it is necessary to perform the TSC measurement under measurement conditions suitable for the sample to be measured. For example, if the sample to be measured is an organic semiconductor and the trap level is derived by TSC measurement for the organic semiconductor, it is necessary to set measurement conditions suitable for deriving the trap level of the organic semiconductor. is there. Here, as typical measurement conditions, the magnitude of the applied voltage applied to the sample when performing TSC measurement, the application time of the applied voltage, from the end of application of the applied voltage to the start of temperature rise of the sample For example, the retention time.

  However, conventionally, measurement conditions for performing TSC measurement are generally determined by a measurement operator (for example, an operator of the measurement apparatus) based on an empirical rule and set in the measurement apparatus. Measurement conditions suitable for the sample to be measured are not always set, and it may take a lot of time to determine the conditions. In particular, when a sample made of an unknown material is an object to be measured, it is necessary to invest a lot of man-hours (labor) such as narrowing down more complicated conditions and verifying reproducibility.

  Therefore, the present invention can easily and quickly determine the measurement conditions suitable for the sample to be measured, and thermally stimulated current measurement capable of performing appropriate TSC measurement according to the determined measurement conditions. It is an object to provide a device, a thermal stimulation current measurement program, and a thermal stimulation current measurement method.

The present invention has been devised to achieve the above object.
A first aspect of the present invention is a thermally stimulated current measuring apparatus that performs thermally stimulated current measurement on a sample to be measured, and provides conditions for measurement conditions necessary for performing thermally stimulated current measurement on the sample. Condition extracting means to perform, condition registering means for registering the measurement condition set by the condition extracting means in a predetermined data storage area, and the sample using the measurement condition registered by the condition registration means in the data storage area And a measurement execution means for measuring a thermally stimulated current.
According to a second aspect of the present invention, in the thermally stimulated current measuring apparatus according to the first aspect, the measurement condition that the condition extracting unit determines the condition is an application to be applied to the sample when performing the thermally stimulated current measurement. It includes at least one of the magnitude of voltage, the application time of the applied voltage, and the holding time from the end of application of the applied voltage to the start of temperature rise of the sample.
According to a third aspect of the present invention, in the thermally stimulated current measuring device according to the first or second aspect, the condition extracting unit is configured such that the size of the return portion in the detected result of the thermally stimulated current measurement is in the detected result. A condition is determined for the holding time from the end of voltage application to the sample to the start of temperature rise of the sample when performing the thermally stimulated current measurement so that it falls within a predetermined ratio of the size of the linear approximation portion And
According to a fourth aspect of the present invention, in the thermally stimulated current measuring device according to the first, second, or third aspect, the condition registering unit is configured to change the condition according to the result of the thermally stimulated current measurement by the measurement executing unit. It is characterized by comprising condition correction means for correcting the contents of the measurement conditions registered in the data storage area.
According to a fifth aspect of the present invention, there is provided a computer mounted on a thermally stimulated current measuring device that measures a thermally stimulated current for a sample to be measured, or a computer connected to the thermally stimulated current measuring device. Condition extraction means for setting conditions for measurement conditions required when performing current measurement, condition registration means for registering the measurement conditions set by the condition extraction means in a predetermined data storage area, and the condition registration means Is a thermal stimulation current measurement program that causes the thermal stimulation current measurement device to perform measurement of thermal stimulation current for the sample while using the measurement conditions registered in the data storage area.
According to a sixth aspect of the present invention, there is provided a thermally stimulated current measurement method for measuring thermally stimulated current for a sample to be measured, wherein conditions are set for measurement conditions required when the thermally stimulated current is measured for the sample. Performing the condition extraction step, the condition registration step for registering the measurement condition set in the condition extraction step in a predetermined data storage area, and the sample using the measurement condition registered in the data storage area in the condition registration step And a measurement execution step of measuring thermally stimulated current with respect to the heat stimulated current.

  According to the present invention, measurement conditions suitable for a sample to be measured can be easily and quickly determined, and appropriate TSC measurement can be performed according to the determined measurement conditions.

It is explanatory drawing which shows an example of schematic structure of the thermally stimulated current measuring apparatus which concerns on this invention. It is explanatory drawing which shows the other example of schematic structure of the thermally stimulated current measuring apparatus which concerns on this invention. It is explanatory drawing which shows a specific example of the outline | summary of a TSC measurement. It is explanatory drawing which shows a specific example of the TSC partial temperature rising method. It is a flowchart which shows the example of the fundamental flow of the process sequence in the thermally stimulated current measuring method which concerns on this invention. It is explanatory drawing which shows a specific example of the detection result of a voltage-current measurement. It is explanatory drawing which shows a specific example of the detection result of the electric current change with respect to time passage. It is explanatory drawing which shows a specific example of the detection result of a TSC global peak measurement. It is explanatory drawing which shows one specific example of the difference in the detection result of the TSC global peak measurement by the difference in collecting voltage. It is explanatory drawing which shows a specific example of the detection result of the electric current change with respect to the wavelength change of irradiation light. It is explanatory drawing which shows a specific example of the detection result of a TSC measurement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, description will be made by dividing into items in the following order.
1. 1. Configuration of thermal stimulation current measuring device 2. Outline of TSC measurement 3. Outline of measurement conditions for TSC measurement 4. Characteristic procedure of TSC measurement Effects of the present embodiment 6. Modified example

<1. Configuration of Thermally Stimulated Current Measuring Device>
First, a schematic configuration of a thermally stimulated current measuring device used for performing TSC measurement will be described.

(First configuration example)
FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a thermally stimulated current measuring apparatus according to the present invention.
The thermal stimulation current measuring device of the illustrated example is roughly configured to include a sample chamber 10, a DC power source 20, a DC minute ammeter 30, and a computer unit 40.

The sample chamber 10 is configured so that the sample 11 to be measured by the TSC measurement is set in the chamber with the electrode 12 sandwiched from above and below. Examples of the sample 11 to be measured include polymer materials, toners, pharmaceuticals and the like in addition to organic semiconductors or inorganic semiconductors.
Further, the sample chamber 10 is provided with a temperature control function 13 so that the room temperature can be kept constant, rapidly cooled, or heated at a constant speed. The temperature control function 13 should just be comprised using the well-known technique.
Further, a rotary pump 15 and a gas supply source 16 are communicated with the sample chamber 10 via an on-off valve 14 so that the indoor environment can be reduced in pressure or a predetermined gas (for example, helium gas) environment. Yes.

  The DC power source 20 applies a voltage to the sample 11 set in the sample chamber 10 through the relay switch 21 and the electrode 12 to cause polarization, charge trapping, and the like inside the sample 11. It is. By applying this voltage, the sample 11 in the sample chamber 10 is excited to cause polarization, charge trapping, and the like.

The direct current microammeter 30 detects a current generated by a depolarization phenomenon, a detrapping phenomenon, or the like in the sample 11 set in the sample chamber 10 via the electrode 12 and the relay switch 31. That is, the direct current minute ammeter 30 detects a direct current minute current for TSC measurement. Therefore, the direct current microammeter 30 can measure a very small current of femtoampere (10 ⁻¹⁵ A).

  The computer unit 40 is for performing operation control necessary for TSC measurement. Specifically, the CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard disk drive). ), A combination of various interfaces and the like. Then, the computer unit 40 causes the CPU to execute a predetermined program stored in the ROM or HDD, whereby the measurement execution unit 41, the monitoring unit 42, the result processing unit 43, the data storage area 44, the condition extraction unit 45, the condition registration The unit 46 and the condition correcting unit 47 are configured to function.

The measurement execution means 41 is a function for performing TSC measurement on the sample 11 set in the sample chamber 10. More specifically, in order to perform TSC measurement on the sample 11, an operation control instruction is given to each part of the thermally stimulated current measuring apparatus represented by the temperature control function 13 of the sample chamber 10, the DC power source 20, and the like. ing.
The monitoring means 42 has a function of detecting the temperature in the sample chamber 10 at the time of TSC measurement, the detection current by the direct current microammeter 30, and the like.
The result processing unit 43 performs a predetermined arithmetic processing, data plot processing, and the like based on the detection result of the monitoring unit 42, and generates TSC measurement result data for the sample 11 set in the sample chamber 10. It is. The TSC measurement result data generated by the result processing means 43 is output by a display device or printer device (not shown) connected to the computer unit 40.

  The data storage area 44 is a function for storing and holding various information necessary for the measurement execution means 41 to execute TSC measurement. Various types of information stored and held in the data storage area 44 include information on measurement conditions for appropriately performing TSC measurement. Details of the measurement conditions for performing the TSC measurement will be described later.

The condition extraction means 45 is a function for determining the measurement conditions necessary for performing TSC measurement on the sample 11 set in the sample chamber 10.
The condition registration means 46 is a function for registering the measurement conditions that the condition extraction means 45 has determined in the data storage area 44.
The condition correction means 47 is a function for correcting the contents of the measurement conditions registered in the data storage area 44 by the condition registration means 46 as necessary.
The details of setting the measurement conditions and correcting the contents will be described later.

A predetermined program for realizing each of these functions (that is, an embodiment of the thermal stimulation current measurement program according to the present invention) is installed and used in the computer unit 40. Prior to the installation, the computer unit 40 It may be provided by being stored in a readable storage medium, or may be provided to the computer unit 40 through a communication line connected to the computer unit 40.
Further, the computer unit 40 in which the thermal stimulation current measurement program is installed is not necessarily installed in the thermal stimulation current measuring device as long as it can give an operation control instruction to each unit of the thermal stimulation current measuring device. Alternatively, it may be connected to the thermal stimulation current measuring apparatus via a communication line.

(Second configuration example)
Next, another schematic configuration example of the thermally stimulated current measuring device will be described.
FIG. 2 is an explanatory view showing another example of the schematic configuration of the thermally stimulated current measuring apparatus according to the present invention.
In addition, about the component same as the 1st structural example mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted here.

The thermally stimulated current measuring device in the example includes a light irradiation mechanism 50.
The light irradiation mechanism 50 irradiates the sample 11 set in the sample chamber 10 with light having a wavelength having energy corresponding to the band gap of the sample 11. However, since it is necessary to irradiate light of different wavelengths depending on the sample 11, the light irradiation mechanism 50 is configured to have a light source capable of changing the wavelength of irradiation light or an optical filter to be interposed. It is possible to use a thing.

In response to the light irradiation from the light irradiation mechanism 50, the sample chamber 10 is provided with a sample table 17 in the chamber, and the sample 11 to be measured is set on the sample table 17. It is configured. Then, the electrode 12 is arranged on a part of the upper surface side of the sample 11 set on the sample table 17, and the light from the light irradiation mechanism 50 is applied to the other portion on the upper surface side where the electrode 12 is not arranged. Will be irradiated.

  In the thermally stimulated current measuring apparatus of the second configuration example as described above, the sample 11 in the sample chamber 10 is excited by performing light irradiation from the light irradiation mechanism 50 in addition to voltage application by the DC power supply 20. As a result, a charge trap or the like is generated in the sample 11.

  In addition, although the 1st structural example and the 2nd structural example were demonstrated here as a schematic structural example of a thermally stimulated current measuring apparatus, the thermally stimulated current measuring apparatus of this embodiment is any of a 1st structural example and a 2nd structural example. Alternatively, the first configuration example and the second configuration example may be selected as necessary.

<2. Overview of TSC measurement>
Next, an outline of TSC measurement performed using the thermal stimulation current measuring apparatus having the above-described configuration will be described.

(General procedure for TSC measurement)
FIG. 3 is an explanatory diagram showing a specific example of an outline of TSC measurement.
Here, the sample 11 to be measured is an organic semiconductor such as a SiC semiconductor or an organic EL device, and a voltage is applied to such a sample 11 using the thermally stimulated current measuring device described in the second configuration example. As an example, the trap level in the sample 11 is measured by light irradiation.

When performing TSC measurement using a thermally stimulated current measuring device, first, a sample 11 to be measured is set in the sample chamber 10, and the temperature control function 13 of the sample chamber 10 is operated in that state. The inside of the sample chamber 10 is cooled from room temperature to a liquid nitrogen region (for example, about −180 ° C.). Then, a voltage of the trapping voltage Vset is applied from the DC power source 20 to the sample 11 in the sample chamber 10, and light irradiation from the light irradiation mechanism 50 is performed, whereby excited carriers (electrons and holes) are emitted. The charge trap in the sample 11 is captured and frozen (see “Step 1” in the figure).

The voltage application of the trapping voltage Vset to the sample 11 is performed until a predetermined application time tset elapses from the start of application. Then, after the application time tset has elapsed, thereafter, the temperature state in the sample chamber 10 is maintained until a predetermined holding time tgset has elapsed. This is because the state of charge trapping in the sample 11 is stabilized by securing the holding time tgset, thereby enabling accurate TSC measurement.

After the holding time tgset has elapsed, after that, the temperature control function 13 of the sample chamber 10 is operated,
The inside of the sample chamber 10 is heated at a constant speed, and the thermal release of electrons or holes from the charge trap in the sample 11 is observed with a DC microammeter 30 as a TSC current (“Step 2” in the figure).
reference). These releases first occur from shallow charge traps (see “P1” in the figure).

When the temperature in the sample chamber 10 is further increased, carriers are released from deeper charge traps in the sample 11 (see “P2” in the figure). The thermal release from the deep charge trap is also observed with the DC microammeter 30 as the TSC current (see “Step 3” in the figure).
When the electron or hole released from the charge trap of the sample 11 is observed with the direct current microammeter 30 as a TSC current, a direct current is applied to the sample 11 in order to guide the moving direction of the electron or hole. It is assumed that a voltage of the collecting voltage Vc is applied from the power source 20. The application of the collecting voltage Vc starts when a certain short-circuit time elapses after the application of the trapping voltage Vset. Then, when the application of the collecting voltage Vc is started, the temperature rise at a constant speed in the sample chamber 10 is started thereafter.

  By analyzing the TSC current value obtained by observation in this way by the result processing means 43 of the computer unit 40, information on the trap level in the band gap can be obtained for the sample 11 to be measured. It will be.

(TSC partial heating method)
By the way, in the TSC measurement, when the temperature inside the sample chamber 10 is raised at a constant speed, a technique called a partial temperature raising method can be adopted.
FIG. 4 is an explanatory view showing a specific example of the TSC partial temperature raising method.
In the TSC partial temperature raising method, the temperature inside the sample chamber 10 is increased stepwise. Therefore, in the TSC partial temperature raising method, the temperature rise width and the temperature interval in each stage are set. Then, the temperature in the sample chamber 10 is increased at a constant rate from a certain temperature increase start temperature (first temperature), and the temperature in the sample chamber 10 is increased from the first temperature by the amount of the temperature increase. Thereafter, the temperature rise is interrupted to cool the inside of the sample chamber 10, and when the temperature in the sample chamber 10 decreases to a temperature (second temperature) obtained by adding a temperature interval to the first temperature, the second temperature is reached. Then, the temperature in the sample chamber 10 is increased again at a constant speed, and the temperature in the sample chamber 10 is increased from the second temperature by the amount of the temperature increase. This is repeated for a specified temperature range.
If the temperature inside the sample chamber 10 is raised by such a TSC partial temperature raising method, the difference in thermal release at each temperature raising stage can be clarified, and the difference is observed by the direct current microammeter 30. As a result, accurate TSC measurement can be realized.

<3. Overview of TSC measurement conditions>
Next, measurement conditions necessary for performing the above-described TSC measurement will be described.

  The “measurement conditions” here are measurement conditions necessary for appropriately performing TSC measurement reflecting the characteristics, measurement purpose, etc. of the sample 11 to be measured. It is a condition that needs to be set in advance for TSC measurement.

Specifically, the measurement conditions include (1) the cooling temperature in the sample chamber 10, (2) the value of the trapping voltage Vset applied to the sample 11, (3) the value of the application time tset of the trapping voltage Vset, (4 ) Value of holding time tgset after application of trapping voltage Vset, (5) value of collecting voltage Vc applied to sample 11, (6) presence / absence of light irradiation on sample 11, (7) light in case of performing light irradiation (8) intensity of light irradiation when light irradiation is performed, and (9) temperature increase rate in the sample chamber 10.
Further, in the case of performing the temperature increase by the TSC partial temperature increase method, in addition to the above (9) the temperature increase rate in the sample chamber 10, (10) the temperature increase range in each step, (11) each step There is a temperature interval between.

These measurement conditions need to be suitable for the sample 11 to be measured, as already described. On the other hand, for these measurement conditions, for example, if the operator of the thermally stimulated current measuring device determines based on empirical rules and sets the thermally stimulated current measuring device, the sample 11 to be measured is not necessarily measured. Therefore, it is not always possible to set measurement conditions suitable for the measurement, and it is necessary to input a large amount of man-hours (manual effort) for setting the conditions.
For this reason, in the present embodiment, in the TSC measurement, in addition to the general procedure described above, the following characteristic procedure is performed.

<4. Characteristic procedure of TSC measurement>
Next, a characteristic procedure of TSC measurement performed using the thermal stimulation current measuring apparatus having the above-described configuration, that is, a characteristic procedure of the thermal stimulation current measuring method in the present embodiment will be described.

(Basic flow of processing procedure)
FIG. 5 is a flowchart showing an example of a basic flow of a processing procedure in the thermally stimulated current measuring method according to the present invention.
When TSC measurement is performed using the thermal stimulation current measuring apparatus having the above-described configuration, first, an operator of the thermal stimulation current measuring apparatus specifies information for specifying the sample 11 to be measured (for example, if it is an organic semiconductor, Information on names of materials constituting the organic semiconductor) is input to the computer unit 40. Then, the computer unit 40 searches the sample 11 for which information has been input to determine whether or not the measurement conditions necessary for the TSC measurement have already been registered in the data storage area 44, and the conditions for the measurement conditions are determined. It is determined whether or not it is necessary (step 101; hereinafter, step is abbreviated as “S”).

  If condition determination is necessary, the computer unit 40 executes a condition extraction step in which the condition extraction means 45 performs condition determination for the measurement conditions (S102). Specifically, conditions are determined for each of the measurement conditions (1) to (9) and, if necessary, each of the measurement conditions (10) and (11). A specific method for determining the conditions for each measurement condition will be described later. When the conditions of each measurement condition are determined, the computer unit 40 executes a condition registration process in which the condition registration unit 46 registers each measurement condition determined in the condition extraction process in the data storage area 44 (S103). ). As a result, the measurement conditions necessary for the TSC measurement on the sample 11 to be measured are registered in the data storage area 44.

  If the measurement conditions are registered in the data storage area 44, then the measurement execution means 41 of the computer unit 40 gives an operation control instruction to each part of the thermal stimulation current measuring device. As a result, a measurement execution step for performing TSC measurement on the sample 11 in the sample chamber 10 is performed while using the measurement conditions in the data storage area 44 (S104). The TSC measurement at this time is performed according to the general procedure already described (see FIG. 3). When TSC measurement is performed, in the computer unit 40, the monitoring means 42 detects the temperature in the sample chamber 10 at the time of TSC measurement, the detected current in the DC microammeter 30, and the result processing means 43 is the monitoring means. The detection result at 42 is analyzed to generate TSC measurement result data.

  After generating the TSC measurement result data, the computer unit 40 analyzes the generated TSC measurement result data, and determines whether or not the measurement conditions used for obtaining the TSC measurement result data need to be corrected (S105). ). If correction is necessary, the computer unit 40 executes a condition correction step in which the condition correction means 47 corrects the contents of the measurement conditions in the data storage area 44 to be corrected (S106). As a result, the measurement conditions registered in the data storage area 44 are corrected as necessary.

  Thereafter, the computer unit 40 repeats the above-described steps from the measurement execution step again if it is necessary to re-execute the TSC measurement under the corrected measurement conditions (S104 to S107). The process ends.

(S102: Condition extraction step)
Here, the condition extraction step (S102) will be described in more detail with a specific example.
In the condition extraction step (S102), for example, conditions are determined for each of the measurement conditions (1) to (11).

  Among these measurement conditions, for each measurement condition of (1), (6), and (9), the specification of the thermal stimulation current measuring device and information for specifying the sample 11 to be measured (for example, an organic semiconductor) It is possible to uniquely determine from the names of constituent materials). Therefore, for each of the measurement conditions (1), (6), and (9), for example, information for associating the information for specifying the sample 11 with the contents of each measurement condition corresponding to the information is previously stored for various samples 11. It can be considered that the data is stored in the data storage area 44 and the condition is determined based on the stored information.

On the other hand, the measurement conditions (2) to (5), (7), (8), (10), and (11) described above are not necessarily based on information that specifies the sample 11 to be measured. It cannot be determined uniquely.
Therefore, in the condition extraction step (S102), a preliminary test as described below is performed in determining the conditions for the measurement conditions (2) to (5), (7), (8), (10), and (11). I do.

(Preliminary test for trapping voltage Vset)
When performing a preliminary test in the condition extraction step (S102), first, the sample 11 itself to be measured in the measurement execution step (S104) to be performed later, or another sample 11 that can be identified with the sample 11 is sampled. Set in the room 10. Then, the inside of the sample chamber 10 is cooled to a temperature (for example, about −180 ° C.) obtained by the determination of the measurement condition (1), and a voltage is applied to the sample 11 from the DC power source 20 in that state. The current change in the sample 11 at that time is detected by the direct current microammeter 30. That is, in the preliminary test for the trapping voltage Vset, voltage-current measurement is performed on the sample 11 to detect a change in current with respect to a change in applied voltage.

FIG. 6 is an explanatory diagram showing a specific example of the detection result of the voltage-current measurement.
As shown in the figure, when the voltage applied to the sample 11 is gradually increased over time, the current in the sample 11 suddenly increases after exceeding the inflection point I ₁ due to the influence of charge trapping and the like. then it exceeds an inflection point I ₂ with an increased rate shows a property that becomes gentle. Such characteristics in mind, the trapping voltage Vset is applied to the sample 11 in the measurement execution process (S104), it is conceivable to set to a voltage value corresponding to the inflection point I _2. However, there is a possibility that the error bar becomes large due to the critical voltage value at this point. Therefore, a margin amount is secured for the inflection point I ₂ by + α, and the voltage value corresponding to the point where the current value is I ₂ + α is set as the value of the trapping voltage Vset. As the margin amount α secured at this time,
For example, the current value is considered to be an amount within the scope of 10% ± 10% of I _2.

By passing through the preliminary test of such a procedure, conditions are determined for the value of the trapping voltage Vset applied to the sample 11 (2) above. The value of the trapping voltage Vset extracted by this condition determination is registered at a predetermined location in the data storage area 44 by the condition registration means 46 of the computer unit 40.

(Preliminary test for application time tset of trapping voltage Vset)
Once the conditions for the trapping voltage Vset have been determined, the condition extraction step (S1
In 02), the conditions for the application time tset of the trapping voltage Vset are determined. In determining the condition of the application time tset, the sample chamber 10 is cooled (for example, −18
In a state of about 0 ° C.), a voltage having a value of the trapping voltage Vset that has been conditioned is applied from the DC power source 20 to the sample 11 in the sample chamber 10. Then, a change in current over time in the sample 11 at that time is detected by the DC microammeter 30. That is, the application time tset
In the preliminary test, a current measurement of the sample 11 is performed to detect a change in current with the lapse of time of voltage application.

FIG. 7 is an explanatory diagram illustrating a specific example of a detection result of a current change with time.
When the trapping voltage Vset is applied to the sample 11 as shown in the figure, the sample 11
The current at has a characteristic that the current value gradually decreases from the beginning of voltage application with the lapse of time of voltage application and then converges to a certain current value. If voltage application is continued as it is, the current in the sample 11 may cause so-called saturation. In consideration of such characteristics, the application time tset of the trapping voltage Vset applied to the sample 11 in the measurement execution step (S104) converges to a certain current value in the sample 11 and causes saturation. It is time when there is nothing.

By passing through the preliminary test of such a procedure, the condition is determined for the value of the application time tset of the above (3) trapping voltage Vset. The value of the application time tset extracted by this condition determination is registered at a predetermined location in the data storage area 44 by the condition registration means 46 of the computer unit 40.

(Preliminary test for holding time tgset after voltage application)
After the conditions for the application time tset of the trapping voltage Vset have been determined, in the condition extraction step (S102), the holding time tgset from the end of the application of the trapping voltage Vset to the start of temperature rise in the sample chamber 10 The condition is determined. When determining the condition of the holding time tgset, the value of the trapping voltage Vset for which the condition is determined for the sample 11 in the sample chamber 10 in a state where the chamber of the sample chamber 10 is cooled (for example, a state of about −180 ° C.). Is applied from the DC power source 20 for the same application time tset. Then, after the preset default holding time has elapsed from the end of voltage application, the temperature rise in the sample chamber 10 is started at the rate of temperature rise obtained by setting the measurement conditions in (9) above, and the sample at that time 11 is detected by a DC microammeter 30. That is, in the preliminary test for the holding time tgset, the TSC measurement is performed on the sample 11 by raising the temperature range to be heated at a constant temperature rising rate, not by the TSC partial temperature raising method. Hereinafter, this TSC measurement is referred to as “TSC global peak measurement”.

FIG. 8 is an explanatory diagram showing a specific example of the detection result of the TSC global peak measurement.
As shown in the figure, the detection result of the TSC global peak measurement has a characteristic of having a linear approximation portion on the rising side and further having a return portion on the previous stage side (low temperature side). The range of the linear approximation portion can be specified by using a known mathematical method. The return portion is caused by the remaining surplus carriers to be released at the holding temperature, and the generation mode differs depending on the value of the holding time tgset. The return part is
The range can be specified by using a well-known mathematical method after grasping each coordinate value of the inflection point where the detection result starts and the detection result changes from falling to rising. The return portion can be suppressed to a small value if the holding time tgset is sufficiently secured. However, in this case, a lot of time is required for the TSC measurement. That is, since there are carriers with different release times, the required length of the holding time tgset differs depending on the sample 11. In consideration of such characteristics, for the holding time tgset to be secured in the measurement execution step (S104), the temperature width of the return portion is, for example, 30 with respect to the temperature width of the linear approximation portion.
It is conceivable to set the magnitude of the time so that it is within 10%, preferably within 10%. That is, in the preliminary test for the holding time tgset, T
SC global peak measurement is performed to detect the size of the return portion relative to the linear approximation portion.

By going through the preliminary test of such a procedure, the above (4) holding time tgset after voltage application
Conditioning is performed on the value of. Specifically, the size (temperature range) of the return portion is within a predetermined ratio (for example, within 30%, preferably 10%, for example) of the size (temperature range) of the linear approximation portion.
The condition for the holding time tgset is determined so as to be within the range of The value of the retention time tgset extracted by this condition determination is registered at a predetermined location in the data storage area 44 by the condition registration means 46 of the computer unit 40. Further, the value of the holding time tgset obtained in this way can also be applied to the case where the measurement execution step (S104) to be performed later performs temperature increase by the TSC partial temperature increase method.

(Preliminary test for collecting voltage Vc)
Once the conditions for holding time tgset have been determined, the condition extraction step (S102)
Then, conditions for the collecting voltage Vc are determined. In determining the condition of the collecting voltage Vc, first, 1/100 to the value of the trapping voltage Vset for which the condition is determined.
Any value corresponding to 1/1 or -1/100 to -1/1 is set as a recommended value. However, in the case where an internal electric field can be generated in the sample 11, for example, it may be set to 0V. And the TSC global peak measurement with respect to the sample 11 is performed with the recommended value, and the waveform of the detection result is obtained.

FIG. 9 is an explanatory diagram showing a specific example of a difference in detection results of TSC global peak measurement due to a difference in collecting voltage.
As shown in the figure, the waveform of the detection result of the TSC global peak measurement shows a characteristic that the rising side is hardly affected by the collecting voltage Vc, but the other side is greatly different depending on the collecting voltage Vc. As for the detection result of this TSC global peak measurement, it is desirable to draw a waveform in which the TSC current rises as the temperature rises, passes the peak, and then returns to its original value (see the waveform at −10 V in the figure). ). Therefore, if the waveform of the detection result is desirable as a result of TSC global peak measurement using the recommended value, the recommended value is set as the value of the collecting voltage Vc. However, if the waveform of the detection result is not desirable, the trapping voltage Vset
A new recommended value is specified within the range of 1/100 to 1/1 or -1/100 to -1/1 of the value of, and the waveform of the detection result of TSC global peak measurement is confirmed for the new recommended value To do.

  By passing through the preliminary test of such a procedure, conditions are determined for the value of the collecting voltage Vc applied to the sample 11 (5) above. The value of the collecting voltage Vc extracted by this condition determination is registered at a predetermined location in the data storage area 44 by the condition registration means 46 of the computer unit 40.

(Preliminary test for irradiation light)
When it is determined that light irradiation is performed on the sample 11 in the condition determination for the measurement condition (6) above, in the condition extraction step (S102), conditions regarding the wavelength and irradiation intensity of the irradiation light are further determined. In determining the conditions of the wavelength of irradiation light and the irradiation intensity, light from the light irradiation mechanism 50 is applied to the sample 11 in the sample chamber 10 in a state where the chamber of the sample chamber 10 is cooled (for example, a state of about −180 ° C.). Irradiate. At this time, the light irradiation mechanism 50 performs light irradiation while changing the wavelength from the long wavelength side to the short wavelength side. Then, the direct current microammeter 30 detects a current change according to the wavelength change of the irradiation light in the sample 11 at that time. That is, in the preliminary test for the irradiation light, the current of the sample 11 is measured to detect a change in current with respect to the wavelength change of the irradiation light.

FIG. 10 is an explanatory diagram illustrating a specific example of the detection result of the current change with respect to the wavelength change of the irradiation light.
As shown in the figure, when the sample 11 is irradiated with light, the current in the sample 11 increases as the wavelength of the irradiated light becomes shorter, and a photocurrent (Photo Current) is generated at a certain wavelength.
) Shows the characteristic of reaching the maximum value. Taking such characteristics into consideration, the measurement execution step (S10
The light irradiated to the sample 11 in 4) is set to a light energy amount Eset that secures a margin amount with respect to the light energy amount Ee when the maximum value of the photocurrent is reached. As the margin amount secured at this time, for example, it is conceivable that the amount of light energy belongs to the range of 10% ± 10% of Ee. Then, the wavelength λset and the irradiation intensity of the irradiation light that can obtain the light energy amount Eset are selected.

  Through the preliminary test of such a procedure, conditions are determined for the wavelength of light when performing (7) light irradiation and the intensity of light irradiation when performing (8) light irradiation. Is called. The wavelength and irradiation intensity of the light extracted by this condition determination are registered at predetermined locations in the data storage area 44 by the condition registration means 46 of the computer unit 40.

(Preliminary test for TSC partial heating method)
If the temperature is to be raised by the TSC partial temperature raising method in the measurement execution step (S104), in the condition extraction step (S102), conditions are set for the temperature rise width and the temperature interval in each stage. In determining the temperature rise width and temperature interval at each stage, TSC global peak measurement is performed in the same manner as in determining the holding time tgset (see, for example, FIG. 8). When the waveform of the detection result of the TSC global peak measurement is obtained, the half width of the waveform is obtained and compared with a predetermined threshold value to determine whether the peak of the waveform is sharp or broad. As a result, if the peak of the waveform is sharp, the temperature interval between each stage is narrowed, and the temperature rise width at each stage is reduced. Further, if the peak of the waveform is broad, the temperature interval between the stages is widened, and the temperature increase width at each stage is increased. Specifically, if the half width of the waveform belongs to a predetermined numerical range, the temperature increase width and temperature interval of each stage are set to predetermined reference values (for example, temperature increase width: 30 ° C., temperature interval: 10 ° C.). However, when the half width of the waveform is smaller than the predetermined numerical range and has a sharp peak, the temperature rise width and temperature interval at each stage are set smaller than the reference value (for example, the temperature rise width: 25 ° C., temperature interval: 5 ° C.) When the half width of the waveform is larger than the predetermined numerical range and has a broad peak, the temperature increase width and the temperature interval of each stage are set larger than the reference value ( For example, the temperature rise width is 40 ° C., the temperature interval is 20 ° C.).

  By passing through the preliminary test of such a procedure, conditions are determined for the temperature rise width in each stage (10) and the temperature interval between each stage (11). The wavelength and irradiation intensity of the light extracted by this condition determination are registered at predetermined locations in the data storage area 44 by the condition registration means 46 of the computer unit 40.

  Each measurement condition set in the condition extraction step (S102) as described above is registered in the data storage area 44 in the condition registration step (S103). Thereafter, in the measurement execution step (S104), TSC measurement is performed on the sample 11 in the sample chamber 10 while using the measurement conditions in the data storage area 44. The measurement execution step (S104) is performed according to the general TSC measurement procedure already described (see FIG. 3). And after completion | finish of a measurement execution process (S104), a condition correction process (S106) is performed as needed.

(S106: Condition correction step)
Next, the condition correction step (S106) will be described in more detail with a specific example.

FIG. 11 is an explanatory diagram showing a specific example of the detection result of the TSC measurement.
In the measurement execution step (S104), when the TSC measurement is performed by the TSC partial temperature raising method, for example, a detection result as shown in FIG. 11 is obtained. In the condition correction step (S106), first, the detection result is analyzed, and it is determined whether or not the measurement condition used to obtain the detection result needs to be corrected. Specifically, for example, when the holding time tgset condition is set for each of the detection results at each stage obtained by the TSC partial temperature raising method (see, for example, FIG. 8).
Similarly, it is analyzed whether the temperature width of the return portion is within 30%, preferably within 10%, for example, with respect to the temperature width of the linear approximation portion. Judge that correction is required.

  When it is determined that correction is necessary, in the condition correction step (S106), the computer unit 40 outputs information indicating that the measurement condition needs to be corrected. Thereby, the operator of the thermal stimulation current measuring device can grasp that the measurement conditions need to be corrected.

The measurement conditions can be corrected as follows.
For example, the setting value of the measurement condition that needs to be corrected is displayed and output from the computer unit 40, and the operator of the thermal stimulation current measuring device operating the computer unit 40 is manually input the corrected setting value.
In addition, for example, when a predetermined operation for permitting correction is performed by the operator of the thermal stimulation current measuring apparatus, the computer unit 40 sets the condition again for the measurement condition that needs to be corrected, and the corrected set value May be automatically specified.

<5. Effects of this embodiment>
According to the thermally stimulated current measuring device, thermally stimulated current measuring program, and thermally stimulated current measuring method described in the present embodiment, the following effects can be obtained.

  In the present embodiment, when the sample 11 is set in the sample chamber 10 with respect to the measurement conditions necessary for performing TSC measurement on the sample 11 to be measured, the condition is automatically determined. Therefore, unlike the conventional case where the operator of the thermally stimulated current measuring apparatus or the like performs the condition setting based on the empirical rule, the condition suitable for the sample 11 to be measured can be determined easily and quickly. It is possible to perform appropriate TSC measurement according to the measurement conditions for which the conditions have been set. This is very effective particularly when the sample 11 made of an unknown material is a measurement target. That is, even in the case where the sample 11 made of an unknown material is a measurement object, unlike the conventional case, it is necessary to invest a lot of man-hours (labor), such as narrowing down complicated conditions and verifying reproducibility. There is no end.

In the present embodiment, as measurement conditions for automatically setting conditions, (2) the magnitude of the trapping voltage Vset applied to the sample 11, (3) the value of the application time tset of the trapping voltage Vset, (4) It includes at least one value of the holding time tgset from the end of application of the trapping voltage Vset to the start of heating of the sample 11. While these measurement conditions have a great influence on the detection result of the TSC measurement, the contents may differ depending on the type of the sample 11 to be measured. Therefore, if these representative measurement conditions are set as conditions for automatically determining conditions, it will be very effective in performing appropriate TSC measurements, and the conditions can be determined easily and quickly. Therefore, it is very convenient for a measurement person who performs TSC measurement.
In particular, regarding (4) the holding time tgset, in this embodiment, the size of the return portion in the detection result of the TSC measurement is within a predetermined ratio (for example, within 30%, preferably within the size of the linear approximation portion in the detection result) For example, the condition is set so that it is within 10%. If such conditions are set, it is possible to reliably release excess carriers while suppressing the time required for TSC measurement in the subsequent measurement execution step (S104). The accuracy of TSC measurement can be improved.

In the present embodiment, the contents of the measurement conditions registered in the data storage area 44 can be modified according to the result of TSC measurement. That is, the result of actual TSC measurement can be fed back to the contents of the measurement conditions in the data storage area 44. Therefore, the measurement conditions can be further optimized by repeatedly modifying the contents of the measurement conditions. In addition, by performing TSC measurement using the measurement conditions after the content correction, it is possible to expect higher accuracy with respect to the result of the TSC measurement.

<6. Modified example>
While embodiments of the present invention have been described above, the above disclosure is intended to illustrate exemplary embodiments of the present invention. That is, the technical scope of the present invention is not limited to the exemplary embodiments described above.

  For example, in the present embodiment, there are cases where specific numerical values are given for the setting values of the measurement conditions, but these numerical values are merely examples, and can be appropriately set as necessary.

DESCRIPTION OF SYMBOLS 10 ... Sample chamber, 11 ... Sample, 12 ... Electrode, 13 ... Temperature control function, 14 ... Open / close valve, 15 ... Rotary pump, 16 ... Gas supply source, 17 ... Sample stand, 20 ... DC power supply, 21 ... Relay switch, DESCRIPTION OF SYMBOLS 30 ... DC microammeter, 40 ... Computer part, 41 ... Measurement execution means, 42 ... Monitoring means, 43 ... Result processing means, 44 ... Data storage area, 45 ... Condition extraction means, 46 ... Condition registration means, 47 ... Conditions Correction means, 50... Light irradiation mechanism

Claims (6)

A thermally stimulated current measuring device for measuring thermally stimulated current for a sample to be measured,
Condition extraction means for setting out the measurement conditions necessary for performing the thermally stimulated current measurement on the sample;
Condition registration means for registering the measurement conditions that the condition extraction means has determined in a predetermined data storage area;
Measurement execution means for performing thermally stimulated current measurement on the sample while using the measurement conditions registered in the data storage area by the condition registration means;
A heat-stimulated current measuring device comprising: The measurement conditions for the condition extraction means to determine the conditions are the magnitude of the applied voltage applied to the sample when performing the thermal stimulation current measurement, the application time of the applied voltage, and the rise of the sample from the end of application of the applied voltage. The heat-stimulated current measuring device according to claim 1, comprising at least one of a holding time until the start of temperature. The condition extraction means applies to the sample when performing the thermal stimulation current measurement so that the size of the return portion in the detection result of the thermal stimulation current measurement is within a predetermined ratio of the size of the linear approximation portion in the detection result. The thermal stimulation current measuring device according to claim 1 or 2, wherein a condition for a holding time from the end of voltage application to the start of temperature rise of the sample is determined. The condition registration unit includes a condition correction unit that corrects the content of the measurement condition registered in the data storage area by the condition registration unit according to a result of the thermal stimulation current measurement by the measurement execution unit. 3. The thermal stimulation current measuring device according to 3. A computer mounted on a thermally stimulated current measuring device that measures thermally stimulated current for a sample to be measured, or a computer connected to the thermally stimulated current measuring device,
Condition extraction means for setting out the measurement conditions necessary for performing the thermally stimulated current measurement on the sample;
Condition registration means for registering the measurement conditions that the condition extraction means has determined in a predetermined data storage area;
A thermal stimulation current measurement program that causes the thermal stimulation current measurement device to function as a measurement execution unit while using the measurement conditions registered in the data storage area by the condition registration unit. . A thermally stimulated current measurement method for measuring thermally stimulated current for a sample to be measured,
A condition extraction step for setting the conditions for the measurement conditions required when performing the thermally stimulated current measurement on the sample;
A condition registration step of registering the measurement conditions obtained in the condition extraction step in a predetermined data storage area;
A measurement execution step of performing thermally stimulated current measurement on the sample while using the measurement conditions registered in the data storage area in the condition registration step;
A thermally stimulated current measurement method comprising: