                             THE THIN-FILM DATABASE

               a new concept in scientific literature searching


                                Dr. Ilana Fried

                             Dr. Alfred Rosenstein

                          INFODISK ltd. P.O.Box 3611

                          Rosh-Ha'ayin 40800, Israel



       The explosion of  scientific information, as  illustrated by  the

       ever growing number of papers published, has now come. When, some

       fifty years  ago  one  could read  "Chemical  Abstracts"  on  the

       commuting train,  and thirty  years ago,  one managed  to read  a

       section or two, today, it is very difficult to keep up with  what

       is being published in one's own very narrow specialty.


       This situation has two results:

          a) while one knows everything on  his own area, the amount  of

             knowledge diminishes very rapidly when one steps out of his

             narrow field. This decreases the chances for creative cross

             fertilization;

          b) when the need to read  about another specialty arises,  the

             work  is   often   delegated   to  juni or  staff   or  t o

             non-scientists (librarians  and  information  specialists),

             thus diminishing  the  exposure of  the  most  experienced,

             senior scientist and engineer to new information.


       The computerized databases available today are no longer of  much

       help. Their reliance on key-words, coupled with the ambiguity  of

       language, complicates even  simple searches.  Moreover, when  one

       needs to look for data, such as pressures or temperatures,  these

       data are usually not searchable  or not given. The time  consumed

       and the frustration of conducting  a literature search, is  known

       to us all.


       Infodisk proposes a new concept in the presentation and retrieval

       of data from the scientific literature. Infodisk's first  product

       is a database on thin films, the TF Database.


       THE APPROACH

       The Infodisk Thin  Film Database  contains only  the 'hard  data'

       from  the  original   published  articles.  Infodisk's   research

       scientists read all available articles on thin films and  extract

       all q uantifiable  info rmation  from  those  dealing  wit h th e

       preparation  and  properties  of  thin  films.  When  an  article

       discusses two materials,  each material makes  the object of  one

       record. The same  record may  be present  in one  or more  files,

       depending on the  application of the  material. Infodisk  created

       complete files, so that searches in more than one file is usually

       unnecessary.


       The result  is  a  database  which  answers  difficult  questions

       quickly (within a few minutes) and easily.


       THE CONTENTS OF THE THIN FILM DATABASE

       The TF Database is divided into seven distinct files:

       1. Microelectronics

       2. Superconductors

       3. Electronic displays

       4. Optics and Optoelectronics

       5. Magnetic Storage

       6. Optical Data Storage

       7. Protective Coatings


       Each record contains 110-120 fields,  which are grouped into  six

       sections:

       1. Bibliography

       2. System Characteristics

       3. Preparation Method

       4. Preparation Conditions

       5. Film Properties

       6. Other Properties and Notes


       The structure of all  files is identical  in all sections  except

       'film properties'.


       The structure of the groups is as follows:

       1. Bibliography

          This section  contains all  bibliographic information  of  the

          article plus one 'reference for more detail' if this reference

          is essential for the understanding of the article


       2. System Characteristics

          This section contains the following fields:

          * Film composition

          * Applications

          * Substrate

          * Buffer layer

          * Top layer

          * Multilayer structure

          * Characterization methods

          * Preparation method


       3. Preparation Method

       This section contains the following fields (please note that  the

       field  "preparation  method"  appears  in  two  places.  This  is

       intentional):

          * Preparation method

          * Material source

          * Dopant source

          * Reactive gas

          * Carrier gas

          * Discharge gas

          * Component ratio

          * Substrate pretreatment

          * System pretreatment

          * Post-deposition treatment

          * Post-deposition processing


       4. Preparation Conditions

       This section contains the following fields. It contains the  data

       on temperatures, pressures, power used in preparation, as well as

       some other data:

          * Background pressure

          * Total pressure

          * Reactive gas pressure

          * Carrier gas pressure

          * Discharge gas pressure

          * Flow rate

          * Source temperature

          * Deposition temperature

          * Growth rate

          * Deposition duration

          * Film thickness

          * Discharge beam current

          * Source characterization

          * Power density

          * Target voltage

          * Other technological parameters


       In most  categories,  two fields  are  provided for  maximum  and

       minimum values.  Some  articles  give  a range  of  one  or  more

       parameters, this information is dealt with by indicating the  two

       extreme values of the parameter.


       6. Other Properties and Notes

       This group contains three fields:

          * Other properties

          * Notes, which  contain  important information  given  by  the

            author

          * Conclusions, which contain  a brief summary  of the  article

            written by the abstractor


       5. Film Properties

       This group is different from one file to the other. Examples:


          Electrical properties

          * Conductivity type

          * Carrier density

          * Band gap

          * Resistivity

          * Conductivity

          * Carrier mobility

          * Dielectric constant

          * Dielectric strength

          * Other electrical properties


          Supeconducting properties

          * Critical temperature (onset)

          * Critical temperature (R=0)

          * Critical current density

          * Critical field

          * Normal state resistivity

          * Low temperature susceptibility


          Optical properties

          * Absorption

          * Spectral characteristics

          * Optical transmittance

          * Refractive index

          * Other optical properties


       Here, too, many categories contain fields for maximum and minimum

       values.


       EXAMPLES OF SEARCHES

       The following problems will be given as examples:

       1. Find all  films that  were deposited  using CVD  or a  related

          method, at temperatures between 100 and 300 deg C.


          The preliminary step is to choose the file  (Microelectronics)

          and function (Carry out a search)

          The first step is to choose all records containing CVD in  the

          'Preparation method' field,  and the function  that links  the

          stages together ('and').

          The  second  stage  i s  to  choose  the  fie ld  'Depositio n

          temperature' and input the two extreme values: 'greater  than'

          100 'and' 'less than' 300.

          Choosing 'end selection' initiates the search and displays the

          results. This process takes less than a minute.


       2. Find all films whose carrier  density values are of the  order

          of 1011&a+.3R per  cm3&a+.3R and were  deposited at rates  greater than  1

          nm/sec.


          The preliminary  stage is  the same  as before.  In the  first

          stage  one   chooses  f rom  'Film   Properties,   Electroni c

          Properties' the category 'carrier density' and inputs the  two

          values: 'greater  than' 1*1011&a+.3R  and  'less than'  1*1012&a+.3R.  The

          logic funcion 'and' concludes this stage.


          From 'Preparation Conditions'  one chooses  'Growth rate'  and

          inputs the value 'greater than 1'.


          Concluding the search by 'end selection' produces the  results

          in a few seconds. Again, the search took less than a minute.


       The searcher  is most  often  surprised by  the small  number  of

       articles retrieved. This  is because  all of  these articles  are

       relevant to  the problem  at hand.  This is  in contrast  to  the

       presently available methods,  where one  gets a  large number  of

       titles, but produces  eventually, after  a lot  of searching  and

       sifting, only a very small number of relevant articles.


       OPERATING THE THIN FILM DATABASEB

       There are five functions to the TF Database:

       1. View records

          One can view the  records in two forms:  a Table Format  which

          shows  up  to  1 7  records  on   the  screen,   facilitatin g

          comparisons, and a  Label Format  which gives  one record  per

          screen and is intended for more detailed viewing.


       2. Carry out a search

          Each and  every field  is  searchable. The  program's  special

          feature  of  "m ixed  fields"   makes  it  po ssible  to  pu t

          explanations next  to  numbers, and  search  the  quantitative

          categories both as  numeric (equal, greater  than, less  than)

          and as textual (contains, does not contain) fields.


       3. Sort data

          Enables the sorting  of the  retrieved data  according to  any

          field. The sort can be  done in acsending or decending  order,

          according to numerical of alpha values.


       4. Find text

          This function  finds  a  string in  the  file,  regardless  of

          category.


       5. Produce a report

          The user  decides which  fields  he/she wants  to put  in  the

          report. Reports  are produced  as ascii  files in  the  active

          directory. There are  two forms of  reports: the Table  format

          facilitates comparison  between records,  but gives  only  the

          first 12 characters in every field; the Label format  presents

          all the data in the chosen fields.


          A special case is when one wants to see all the data from  the

          retrieved articles, in all  non-vacant fields. This option  is

          also available.


       CONCLUSIONS

       Infodisk has succeeded in preparing a data-base that shortens the

       time required to make literature searches from days to minutes.


       The implications of this accomplishment are:

       * less time  is spent  in the  library, more  time spent  in  the

         laboratory;

       * it is  now  possible, investing  only  little time,  to  search

         outside  one's  own  specialty,  increasing  the  chances   for

         creative fertilization;

       * everybody will use this  database: scientists, both senior  and

         junior, students, information specialists;

       * students can be given "real life" excersizes, exposing them  to

         real researchproblems at an earlier stage in their education;

       * writing reviews, whether for  publication or for internal  use,

         becomes a mucheasier task.



       FOR INFORMATION ON THE ACQUISITON OF THE DATABASE PLEASE CONTACT

            INFODISK ltd. Tel +972-3-931 8669

                          Fax +972-3-930 1049

                          P.O. Box 3611 Rosh Ha'ayin, 40800 Israel

                          e-mail: INFODISK@Zeus.Datasrv.co.il


