CN1052811C - Multi-alkali photoelectric cathode resistance process tech. - Google Patents
Multi-alkali photoelectric cathode resistance process tech. Download PDFInfo
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- CN1052811C CN1052811C CN96117159A CN96117159A CN1052811C CN 1052811 C CN1052811 C CN 1052811C CN 96117159 A CN96117159 A CN 96117159A CN 96117159 A CN96117159 A CN 96117159A CN 1052811 C CN1052811 C CN 1052811C
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Abstract
The present invention discloses a multi-alkali photoelectric cathode resistance method technology. The multi-alkali photoelectric cathode resistor method technology is characterized in that two resistor measurement electrodes are plated on a cathode substrate and are also connected with fixing direct-current voltage and a resistor in series, the change of voltage on the resistor is recorded by an x-t recording instrument, and then an Sb+K process, a Na process, a Sb and K alternation process, a Cs process and a Sb and Cs alternation process are successively carried out. The present invention has the advantages of strong manufacturing technology regularity, single process determination, simple control, simple monitoring appliance and capability of achieving the calculation of a manufacturing process, and therefore, the present invention enhances production efficiency. The present invention is widely suitable for the fields of weak-light image intensifiers, photomultiplier tubes, etc.
Description
The invention relates to a photoelectric technology, in particular to a method for manufacturing a multi-alkali photocathode.
At present, the cathode is polybase Na2The KSb (Cs) manufacturing method adopts a photocurrent process, and the process takes photocurrent as a feedback monitoring parameter, and determines the supply of alkali metal amount by monitoring the magnitude and the change of the photocurrent and analyzing and judging according to the experience of an operator. Most typically, the photocurrent method disclosed in U.S. Pat. No. 3658400 uses photocurrent as a feedback monitoring parameter, and during the manufacturing process, alkali metal is supplied when the photocurrent reaches a maximum value and drops to a few percent of the maximum value, but during the actual manufacturing process of the multi-alkali photocathode, the alkali metal supply cannot be determined completely according to the process specification, and the alkali metal supply must be determined empirically, so that the multi-alkali cathode is damaged during the manufacturing process, especially during the surface treatment process, without paying attention. Another disadvantage of the photocurrent process is the need for highly accurate weak current detection equipment.
The invention aims to provide a method for manufacturing a multi-alkali cathode, which determines the supply amount of alkali metal according to the resistance and the change of the multi-alkali cathode.
The purpose of the invention is realized as follows: plating two resistance measuring electrodes on a cathode substrate, connecting the resistance measuring electrodes with a fixed direct current voltage and a resistor in series, and recording the change of the voltage on the resistor by using an x-t recorder; secondly, evaporating K at 180-220 ℃ simultaneously3And Sb, stopping after the voltage is increased for 0.5-1.5 minutes, and reducing the voltage after the voltage is stopped, wherein the process mainly forms K3Sb; thirdly, evaporating Na at the temperature of 180-220 ℃ to ensure that the voltage rises to the maximum value and then falls for 0.8-1.2 minutes and then stopping; fourthly, evaporating Sb at the temperature of 180-220 ℃ to increase the voltage until the voltage rises and turnsStop coating by vaporization Sb when some, coating by vaporization K simultaneously, stop coating by vaporization K when minimum value point appears in voltage reduction, repeated coating by vaporization Sb and K, when the position that minimum value point appears in last coating by vaporization K voltage reduction is higher than or equal to the position that minimum value point appears in last voltage reduction, stop coating by vaporization K, this process is mainly that formation and constantly thickening Na2KSb; step five, continuously repeating the processes of the step three and the step four until the required Na is obtained2The thickness of the KSb layer; sixthly, evaporating Cs at the temperature of 170-160 ℃ to reduce the voltage, stopping evaporating Cs when the voltage is reduced to a minimum value point, then increasing the voltage, and evaporating Cs again when the voltage increase rate is reduced, wherein the processis repeated for 2-4 times, so that the Na is evaporated2Obtaining a layer of Cs on the KSb surface3A Sb layer; and a seventh step of evaporating Sb at a temperature of 160-145 ℃ to increase the voltage, stopping when the voltage rises to an inflection point, and then reducing the voltage. When the voltage drop rate is reduced, the evaporation Cs enables the voltage to be further reduced, when the voltage drop has a minimum value point, the evaporation Cs is stopped, then the Sb is evaporated, and the alternating process is repeated for 2-4 times to form Cs with a certain thickness3SbAnd (3) a layer.
The manufacturing method adopts the cathode resistance as a feedback monitoring parameter, and the purpose of monitoring the cathode resistance is to control the alkali metal supply process instead of measuring the absolute value of the cathode resistance, so that the invention uses a certain voltage and a certain resistance to be connected with the cathode resistance in series to form a loop, thus, when the cathode resistance changes, the voltage on the series resistance changes along with the change, and the change of the cathode resistance can be indirectly monitored by monitoring the voltage change on the series resistance. When the voltage signal of the series resistor is recorded by an x-t recorder, the change rule of the cathode in the manufacturing process can be obtained, and the manufacturing process of the polybase cathode can be controlled reversely by using the change rule. The process comprises the following steps:
the direct current voltage in the loop is 1-5V, and the resistance value of the series resistor and the resistance value of the cathode resistor are in the same order of magnitude. In the manufacturing method, it is important to monitor the change law of the cathode resistance, so that during the process of recording the change of the resistance, the unchanged component can be reduced, while the changed component can be amplified, for this purpose, a variable voltage with a value less than or equal to the direct voltage can be connected in series in the loop formed by the series resistance and the recorder. When the value of the variable voltage is zero, the recorder records the actual resistance value on the series resistor, and when a certain adjustable voltage is added, the voltage value recorded by the recorder removes the value of the adjustable voltage. After the adjustable voltage value is removed, the sensitivity of the recorder is improved, i.e. the variable part of the voltage curve can be amplified. The sensitivity of the recorder and the magnitude of the variable voltage can be adjusted according to actual needs, and in principle, the rule of resistance change is obviously recorded. At the beginning of manufacturing the cathode, the monitored voltage is zero because the cathode substrate does not contain any alkali metal, and the alkali metal is gradually deposited on the cathode surface along with the progress of the manufacturing process, so that the conductive characteristic of the cathode is enhanced, the resistance is reduced, and the monitored voltage is increased. When a short circuit occurs between the two measuring electrodes on the cathode face, the monitored voltage value is equal to the value of the direct voltage applied in the series circuit (the variable voltage is set to zero). Therefore, during the manufacturing of the cathode, the voltage varies always between zero and the value of the applied dc voltage.
Compared with the prior art, the invention has the following remarkable advantages: 1. the manufacturing process has stronger regularity, and the process is definite and single, so the control is simpler, and the experience of an operator is avoided; 2. the monitoring equipment is simpler, and the production cost is reduced; 3. the computerization ofthe manufacture of the multi-alkali cathode is easily realized, thereby greatly improving the production efficiency. 4. The method is suitable for some multi-alkali cathode manufacturing environments which are inconvenient for placing and processing light sources. The invention is widely applied to the fields of micro-light image intensifiers, photomultiplier tubes and the like.
The invention is described in more detail below with reference to the following figures and examples:
FIG. 1 is a schematic diagram of a resistance measurement circuit of the present invention.
FIG. 2 is a process curve for the K + Sb and Na processes of the present invention.
FIG. 3 is a process curve of the Sb and K alternating process of the present invention.
Fig. 4 is an enlarged view of the process curve of the two Sb and K alternation processes in fig. 3.
Fig. 5 is a process curve of the Cs process of the present invention.
FIG. 6 is a process curve of Sb and Cs alternating process according to the present invention.
Example (b): taking the production of the phi 18mm generation micro-optical image intensifier multi-alkali photocathode as an example, the production is carried out on the basis of a chromate process, so that the K current, the Sb current and the like in the following processes refer to the heating current of the alkali metal installation tube. Two measuring electrodes made of silver (Ag) or aluminum (Al) and having a size of 3 × 2mm are vapor-deposited on the cathode surface2. The series voltage is 2V, the series resistance is 250K omega, the speed of the recorder is 1cm/min, the sensitivity is 2V, the variable voltage is set to zero, the temperature of the alkali metal generator is regulated to 350 ℃, and the vacuum degree of the device is less than or equal to 10-7And (5) torr. The manufacturing process curve shown in the drawing is a curve of the change in the resistance of the cathode recorded by a recorder during the manufacturing process, and is reflected in the form of a change in voltage, and therefore, the following description of the process is given in terms of a change in voltage. In addition, the numbers in brackets in the process correspond to the numbers in circles in the process curves.
a. K + Sb process. The following procedure was carried out at a temperature of 200 ℃ and the process curve for K + Sb is shown in FIG. 2. The K current is adjusted from small to large until the monitored voltage rises. Then, the magnitude of the K current is further adjusted so that the voltage rises at a constant rate of about 45 degrees to the time axis (1). After about 1.5 minutes of voltage rise, the K current and Sb current were increased stepwise until the rate of rise of the voltage curve was accelerated (2). After 1 minute, the K current and Sb current were turned off in sequence (3). At this point, the voltage again drops at a rate equal to the rate of rise (4). When the voltage dropped for half a minute, the Na current was turned on (5).
b. And (4) Na process. The following procedure was carried out at a temperature of 200 ℃ and the process curve is shown in FIG. 2. After switching on the Na current, the voltage changes slowly (6). After about 3 minutes, the voltage rises at a faster rate (7), drops at a faster rate (9) after a maximum (8), and the Na current is turned off (11) after about 1 minute of decrease (10) in the rate of voltage drop.
c. Sb and K alternate process. The following process is carried out at a temperature of200 ℃, and the process curve is shown in fig. 3 and fig. 4, and fig. 4 is an enlarged view of the Sb and K alternating process of two times in fig. 3. In the manufacturing process of the multi-alkali cathode, the Sb and K alternating process is carried out for a plurality of times, and because the Sb and K alternating process is basically the same in each time, one Sb and K alternating process in the Sb and K alternating process is selected for illustration. After the last Sb and K are finished (12), Na current is turned on, and the voltage rises and then falls after a maximum value (13). When the drop occurs to a minimum (14), the Na current is turned off. The Na current was turned off, and then the Sb current was turned on to increase the voltage. When the voltage rises to (15), the Sb current is turned off, while the K current is turned on. (14) The distance from the first end (15) to the second end (14) is 2-2.5 times the distance from the second end (13). After the K current is turned on, the voltage drops, and when the voltage drops to a minimum value (16), the Sb current is turned on and the voltage rises again. The Sb current is turned off when the voltage rises to (17). (16) The distance between (17) and (16) is about half the distance between (15) and (16). After the Sb current is turned off, the voltage drops again, and when the voltage drop occurs to a minimum (18), the Sb current is turned on. (18) The distance between (15) and (16) is approximately equal to the distance between (19) and (16). After the Sb current is turned off, the voltage drops again, and when the voltage drop occurs to a minimum value (20), the Sb current is turned on. After the Sb current is turned on, the voltage rises again, and when the voltage rises to the point where the inflection point appears (21), the Sb current is turned off. The presence of the inflection point can be seen on the recorder, when the inflection point is reached, there is a pause in the recording nib of the recorder. If the Sb current is not turned offat this time, the voltage will continue to rise at a faster rate. If this occurs during the Sb, K alternation process, the cathode will be damaged. After the Sb current is turned off, the voltage drops again. The Sb current is turned on (22) when the voltage drop rate is slowed. After opening the Sb current, the voltage rises again. The Sb current is turned off (23) when the voltage rises to the point where the inflection point appears. After the Sb current is turned off, the voltage drops again. The Sb current is turned on when the voltage drop occurs to a minimum (24). After the Sb current is turned on, the voltage rises again. The Sb current is turned off (25) when the voltage rises to the point where the inflection point appears. After the Sb current is turned off, the voltage drops again. The K current is turned off (26) when the voltage drop occurs to a minimum value. At this point a complete Sb, K alternation process is complete.
In the process of one Sb, K and alternating process, the steam Sb in the first three Sb and K alternating processes is tentative, namely the Sb current is turned off when no inflection point appears in the voltage rise. The steam Sb is taken as a characteristic point of the current of the steam Sb when the voltage rises to the inflection point. And when the inflection point position of the later Sb evaporation is lower than or equal to the inflection point position of the former Sb evaporation (or after the Sb current is turned off, the position of the minimum value point of the voltage drop caused by the K evaporation is higher than or equal to the position of the minimum value point of the last voltage rise caused by the K evaporation), the K current is turned off, and thus, the complete Sb and K alternating process can be finished.
In addition, in the first Sb and K alternation process from (11), the cathode material composition is not completely Na at this time2KSb, therefore, the number of Sb andK alternation may be large or small in the Sb and K alternation process at the beginning. In this embodiment, Sb and K are alternated only three times.
d. The Cs process. The following processes are carried out at a temperature of 170-160 ℃, and the process curve is shown in FIG. 5. After the Sb, K alternating to obtain the desired thickness, the Sb, K alternating process may be stopped. The temperature should be lowered, during which the voltage is increased continuously, the process curve is changed from (27) to (28), and the Cs current is turned on when the temperature reaches 170 ℃. After turning on the Cs current, the voltage drops and, by the time of occurrence of a minimum value (29), the Cs current is turned off. After the Cs current is turned off, the voltage rises again. The Cs current (30) is turned on when the rate of voltage rise slows (30). After turning on the Cs current, the voltage drops again. The Cs current is turned off (31) when the voltage drops to a minimum value. After the Cs current is turned off, the voltage rises again. When the rate of voltage rise is slowed (32), the Cs current is turned on. After turning on the Cs current, the voltage drops again. The Cs current is turned off (33) when the voltage drops to a point where a minimum value occurs. After the Cs current is turned off, the voltage rises again. When the rate of voltage rise is slowed (34) indicating the end of the Cs process, the temperature should not be below 160 ℃.
e. Sb and Cs alternate process. The following processes are carried out at a temperature of 160 ℃ to 145 ℃, and the process curve is shown in FIG. 6. After the Cs process is over (34), Sb current is turned on and the voltage rises. When the voltage rises to the point where the knee occurs (35), the Sb current is turned off. After the Sb current was turned off, the voltage dropped. When the voltage drop rate is slowed (36), the Cs current is turned on, after whichthe voltage drops further. When the voltage drops to the point where the minimum occurs (37), the Cs current is turned off. After that, the Sb current is turned on and the voltage rises. When the voltage rises to the point where the knee occurs (38), the Sb current is turned off. After the Sb current was turned off, the voltage dropped. When the voltage drop rate is slowed (39), the Cs current is turned on, after which the voltage drops further. When the voltage drops to the occurrence of a minimum (40), the Cs current is turned off. After which the Sb current is turned on and the voltage rises again. When the voltage rises to the point where the knee occurs (41), the Sb current is turned off. After the Sb current was turned off, the voltage dropped. When the voltage drop rate is slowed (42), the Cs current is turned on, after which the voltage drops further. When the voltage drops to the point (43) where the minimum value appears, the Cs current is turned off. So that the Sb and Cs alternating process is finished, and the temperature in the process is not lower than 145 ℃.
Claims (2)
1. A method for manufacturing a multi-alkali photocathode is characterized in that:
plating two resistance measuring electrodes on a cathode substrate, connecting the resistance measuring electrodes with a fixed direct current voltage and a resistor in series, and recording the voltage change on the resistor by using an x-t recorder;
step two, evaporating K and Sb at 180-220 ℃ simultaneously, stopping after the voltage rises for 0.5-1.5 minutes, and reducing the voltage after stopping;
thirdly, evaporating Na at the temperature of 180-220 ℃ to ensure that the voltage rises to the maximum value and then falls for 0.8-1.2 minutes and then stopping;
evaporating Sbat the temperature of 180-220 ℃, enabling the voltage to rise, stopping evaporating Sb when the voltage rises and an inflection point appears, evaporating K at the same time, stopping evaporating K when the voltage drops and an extremely small value point appears, and repeatedly evaporating Sb and K until the position of the extremely small value point appearing in the voltage drop of the next evaporation K is higher than or equal to the position of the extremely small value point appearing in the voltage drop of the previous evaporation K, stopping evaporating K;
step five, continuously repeating the processes of the step three and the step four until the required Na is obtained2The thickness of the KSb layer;
sixthly, evaporating Cs at the temperature of 170-160 ℃ to reduce the voltage, stopping evaporating Cs when the voltage is reduced to a minimum value, then increasing the voltage, and evaporating Cs again when the voltage increase rate is reduced, wherein the process is repeated for 2-4 times;
seventhly, evaporating Sb at 160-145 ℃ to enable the voltage to rise, stopping when the voltage rises to the inflection point, then enabling the voltage to fall, enabling the voltage to further fall when the voltage falling rate is reduced, stopping evaporating Cs when the voltage falls to the minimum point, then evaporating Sb again, and repeating the alternating process for 2-4 times to form Cs3And an Sb layer.
2. The method of claim 1, wherein a variable voltage is connected in series to the circuit formed by the resistor and the x-t recorder, and the variable voltage is less than or equal to a dc voltage.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96117159A CN1052811C (en) | 1996-11-06 | 1996-11-06 | Multi-alkali photoelectric cathode resistance process tech. |
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| CN96117159A CN1052811C (en) | 1996-11-06 | 1996-11-06 | Multi-alkali photoelectric cathode resistance process tech. |
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| CN1181608A CN1181608A (en) | 1998-05-13 |
| CN1052811C true CN1052811C (en) | 2000-05-24 |
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| CN96117159A Expired - Fee Related CN1052811C (en) | 1996-11-06 | 1996-11-06 | Multi-alkali photoelectric cathode resistance process tech. |
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| CN101393837B (en) * | 2008-11-10 | 2010-06-02 | 中国兵器工业第二〇五研究所 | Photocathode of nano second response gleam image intensifier and manufacturing method thereof |
| CN112802726B (en) * | 2021-01-14 | 2023-04-11 | 北方夜视技术股份有限公司 | Method for improving sensitivity uniformity of multi-alkali photocathode |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3658400A (en) * | 1970-03-02 | 1972-04-25 | Rca Corp | Method of making a multialkali photocathode with improved sensitivity to infrared light and a photocathode made thereby |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3658400A (en) * | 1970-03-02 | 1972-04-25 | Rca Corp | Method of making a multialkali photocathode with improved sensitivity to infrared light and a photocathode made thereby |
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