1、Designation: E1855 10E1855 15Standard Test Method forUse of 2N2222A Silicon Bipolar Transistors as NeutronSpectrum Sensors and Displacement Damage Monitors1This standard is issued under the fixed designation E1855; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the use of 2N2222Asilicon bipolar transistors as d
3、osimetry sensors in the determination of neutronenergy spectra,spectra and as silicon 1-MeV(Si)1 Mev(Si) equivalent displacement damage fluence monitors.1.2 The neutron displacement damage is especially valuablein silicon can serve as a neutron spectrum sensor in the range 0.1to 2.0 MeV when fission
4、 foils are not available. It has been applied in the fluence range between 2 1012 n/cm2 andto 1 1014n/cm2 and should be useful up to 1 1015 n/cm2. This test method details the steps for the acquisition and use of silicon 1-MeV1Mev(Si) equivalent fluence information (in a manner similar to the use of
5、 activation foil data) for the determination of neutronspectra.for the partial determination of the neutron spectra by using 2N2222A transistors.1.3 In addition, this sensor can provide important confirmation of neutron spectra determined with other sensors, and Thissensor yields a direct measuremen
6、t of the silicon 1-MeV 1 Mev equivalent fluence by the transfer technique.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with it
7、s use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryrequirements prior to use.2. Referenced Documents2.1 The ASTM standards E170, E261, and E265 provide a background for understanding how sensor
8、s are used in radiationmeasurements and general dosimetry. The rest of the standards referenced in the list discuss the choice of sensors, spectrumdeterminations with sensor data, and the prediction of neutron displacement damage in some semiconductor devices, particularlysilicon.2.2 ASTM Standards:
9、2E170 Terminology Relating to Radiation Measurements and DosimetryE261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation TechniquesE265 Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32E720 Guide for Selection and
10、Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-HardnessTesting of ElectronicsE721 Guide for Determining Neutron Energy Spectra from Neutron Sensors for Radiation-Hardness Testing of ElectronicsE722 Practice for Characterizing Neutron Fluence Spectra in Terms of an Equiv
11、alent Monoenergetic Neutron Fluence forRadiation-Hardness Testing of ElectronicsE844 Guide for Sensor Set Design and Irradiation for Reactor Surveillance, E 706 (IIC)E944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, E 706 (IIA)E1854 Practice for Ensuring Test
12、 Consistency in Neutron-Induced Displacement Damage of Electronic PartsE2005 Guide for Benchmark Testing of Reactor Dosimetry in Standard and Reference Neutron FieldsE2450 Practice for Application of CaF2(Mn) Thermoluminescence Dosimeters in Mixed Neutron-Photon Environments1 This test method is und
13、er the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applicationsand is the direct responsibility of Subcommittee E10.07 onRadiation Dosimetry for Radiation Effects on Materials and Devices.Current edition approved Oct. 1, 2010Oct. 1, 2015. Published October 2010November 2015. Origina
14、lly approved in 1996. Last previous edition approved in 20052010as E1855 05E1855 10. 1. DOI: 10.1520/E1855-10.10.1520/E1855-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information,
15、 refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict al
16、l changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
17、59. United States13. Terminology3.1 Symbols:1 = the silicon 1-MeV 1 Mev equivalent fluence (see Practice E722).hFE = ic/ib where ic is the collector current and ib is the base current, in a common emitter circuit.4. Summary of Test Method4.1 Gain degradation of 2N2222Asilicon bipolar transistors mea
18、sured in a test (simulation) environment is compared with thatameasured in a reference neutron environment. The 1r in the reference environment is derived from the known reference spectrumand is used to determine a measured 1t in the test environment (1,2)3 by the transfer technique. . The subscript
19、s r and t refer tothe reference and test environments respectively.4.2 The measured 1t may be used as a sensor response in a spectrum adjustment code in a manner similar to the use ofcombined with reaction foil activities to determine the spectrum (3,4).4.3 Spectra compatible with the responses of m
20、any sensors may be used to calculate a more reliable measure of the displacementdamage.5. Significance and Use5.1 The neutron spectrum in a test (simulation) environment test spectrum must be known in order to use a measured deviceresponse in the test environment to predict the device performance in
21、 an operational environment (see Practice (E1854). Typically,neutron spectra are determined by use of a set of sensors that have with response functions that are sensitive over the neutronenergy region to which the device under test (DUT) responds (see Guide (E721). In particular, for For silicon bi
22、polar devicesexposed in reactor neutron spectra, this effective energy range is between 0.01 and 10 MeV. A typical set of activation reactionsthat lack fission reactions from nuclides such as 235U, 237Np, or 239Pu, will have very poor sensitivity to the spectrum between0.01 and 2 MeV. For a pool-typ
23、e reactor spectrum, 70 % of the DUT electronic damage response may lie in this range. Often,fission foils are not included in the sensor set for spectrum determinations because their use must be licensed, and they requirespecial handling for health physics considerations. The silicon transistors pro
24、vide the needed response to define the spectrum inthis critical range.5.2 If fission foils are a When dosimeters with a significant response in the 10 keV to 2 MeV energy region, such as fission foils,are unavailable, silicon transistors may provide a dosimeter with the needed response to define the
25、 spectrum in this critical energyrange. When fission foils are part of the sensor set, the silicon sensor provides confirmation of the spectrum shape.spectral shapein this energy region.5.3 Bipolar Silicon bipolar transistors, such as type 2N2222A, are inexpensive, are smaller than fission foils con
26、tained in aboron ball, and are sensitive to a part of the neutron spectrum important to the damage of modern silicon electronics. They alsocan be used directly in arrays to map 1-MeV(Si) equivalent 1 Mev(Si) equivalent displacement damage fluence. The proper setof steps to take in reading the transi
27、stor-gain degradation is the primary subject of described in this test method.5.4 Fig. 1 shows the The energy-dependence of the displacement damage function for silicon. As can besilicon is found inE722seen from the figure, the . The major portion of the response for the silicon transistors will gen
28、erally be above 100 keV. Thecurrently recommended silicon damage function is listed in Practice E722.6. Apparatus6.1 A transistor with The 2N2222A silicon bipolar transistor has a demonstrated response in agreement with calculated 1values in widely varied environments is(5). the silicon bipolar tran
29、sistor 2N2222A. It is recommended that three or more of thesetransistors be calibrated together and used at each location to be characterized. At least three otherstransistors should be used astemperature correction devices (control devices) during readout. control devices. The control transistors s
30、hould be exposed onetime to a calibration exposure of about 1.0 1013 n/cm2 1-MeV(Si) 1 Mev(Si) equivalent fluence and then annealed (baked out)at 180C for 24 h followed by ambient air cooling before being used as controls. These control transistors are not exposed againto radiation during the testin
31、g steps, but are read with the exposed transistors to provide temperature correction.6.2 A dry oven for annealing is needed to stabilize the gain after both the calibration-exposure and gain readout are completedfor the reference environment. The oven shall be able to maintain the set temperature to
32、 within 63.0C at 80C and at 180C. Itwould be prudent to have a timer for automatic shutdown and an emergency power system (UPS). Shutdown with a timer willrequire a door-opening mechanism for ambient air-cooling.6.3 An electronic system is required to maintain appropriate transistor bias and current
33、s and to read the currents for the gainmeasurements. It is recommended that a programmable semiconductor parameter tester (such as a Hewlett Packard 4145A) beused.Aprogrammable tester can operate in pulsed mode to control heating effects and provide gain values quickly. The parameter3 The boldface n
34、umbers in parentheses refer to a list of references at the end of this test method.E1855 152tester determines the common emitter current gain by injecting a pulse of current into the base region, measuring the collectorcurrent, and determining the current ratio ic/ib at a fixed bias of 10 V. The bia
35、s voltage is measured between the collector and thebase (see Ref (56).6.4 Areference neutron source (see Guide (E2005) for calibration of the transistors is required. The neutron fluence and neutronfluence spectrum of the reference source must be known. National Institute for Standards and Technolog
36、y (NIST) benchmark fields(67) are recommended for use as primary standards, and a well characterized Fast Burst Reactor (FBR), fast burst reactor, suchas the one at White Sands Missile Range, is recommended as a reference benchmark field.6.5 A suitable monitor, such as a nickel foil shouldfoil, shal
37、l be exposed along with the transistors during calibration to relateto the magnitude of the neutron fluence. exposures. A photon-sensitive detector such as a CaF2 thermoluminescentthermolume-nescence detector (TLD) shall be included in each test package to monitor the gamma-ray dose so that a correc
38、tion can be madefor the transistor damage from gamma-rays. gamma ray dose. Care must be taken in the determination of the gamma environmentto correct for any neutron response from the photon-sensitive detector that is used. Practice E2450 provides guidance on how tocorrect a CaF2:Mn TLD for the neut
39、ron response.NOTE 1Ionizing dose is produced by photon irradiation in the bulk silicon and SiO2. The ionizing dose can induce trapped holes and interface statesin the oxide of the silicon devices. This resulting trapped charge can induce electric fields that change the gain in a bipolar device.7. De
40、scription of the Test Method7.1 2N2222A transistors exhibit a range of initial gain values and responses, but each responds linearly with 1-MeV(Si)equivalent 1 Mev(Si) equivalent displacement damage fluence, 1, at fixed collector current according to the Messenger-Sprattequation (78), if gamma rays
41、do not contribute to the change of gain.1hFE21hFEO 5K1MeV! (1)The term hFEO is the common emitter current gain at some fixed collector current before irradiation in the test environment, andhFE is the same quantity measured at the same collector current after irradiation. K is the damage constant. I
42、f gamma-ray dosecontributes to the change in the reciprocal of the gain, then that contribution must be subtracted from the left side of Eq 1 (see8.3).7.2 A semiconductor parameter analyzer may be used to determine hFE. A basic schematic circuit used by semiconductoranalyzers for measuring hFE = ic/
43、ib is shown in Fig. 21. A semiconductor parameter analyzer may be used to determine hFE. Anyequivalent method for making the electrical measurement is acceptable but the acceptable. The experimenter must ensure that thecurrents do not exceed the limits detailed in 8.1.2 and 8.1.3.7.3 Since K differs
44、 for each transistor, each must be calibrated. When thecalibrated; see paragraph 8.1.1technology ofmanufacture is such that the . Ks within a batch are the same to within a few percentage points, a calibration by batch may besatisfactory. A typical value for K is about 1.5 101.5 101515 cm2/neutron f
45、or a collector current of 1 mA.7.4 The linearity of response of a given batch of transistors shall be verified by exposure of samples of the batch to at least threelevels of neutron fluence covering the range in which the devices will be used.7.5 The calibration is accomplished by exposing the trans
46、istors in a reference field for which the absolute values of the neutronfluence spectrum are known over the neutron energy range in which significant damage is caused. The 1-MeV(Si) equivalent 1Mev(Si) equivalent displacement damage fluence of the reference environment, 1r, is obtained by folding th
47、e spectrum with thesilicon displacement damage response as is described in Practice E722. The gain values, hFEO before irradiation, and hFE afterirradiation are measured, and the left side of Eq 1 is calculated. The following quantity can be defined.S1h D 5 1hFE2 1hFEO(2)FIG. 21 Schematic for Transi
48、stor Read-OutE1855 153This is the change in reciprocal gain. A subscript of r is used to denote the reciprocal gain change in the reference calibrationenvironment. A subscript of t is used to denote the reciprocal gain change in the test or unknown environment. This measurementand the known value of
49、 1r in the reference environment provide the calibration for the transistor, K.7.6 When the (1/h) is measured in the unknown test environment, the 1t can be found in the following manner. Take theratio of equations (Eq 1) for the reference and test environments and rearrange the terms to yield Eq 3 (see Ref (3).).1t 5S1h DtS1h Dr 1r 5 1KS1h Dt(3)7.7 The 1t is the quantity needed as a sensor value in the spectrum determination procedure. The (1/h)t is the change in thereciprocal gain induced by the test environment. For ne
