HAL Id: jpa-00229660
https://hal.archives-ouvertes.fr/jpa-00229660
Submitted on 1 Jan 1989
HAL
is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire
HAL, estdestinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
SCANNING ISOTHERMAL CURRENT TRANSIENT SPECTROSCOPY (SICTS) FOR DEEP LEVEL
CHARACTERIZATION
Y. Tokumaru, H. Okushi, H. Naka
To cite this version:
Y. Tokumaru, H. Okushi, H. Naka. SCANNING ISOTHERMAL CURRENT TRANSIENT SPEC-
TROSCOPY (SICTS) FOR DEEP LEVEL CHARACTERIZATION. Journal de Physique Colloques,
1989, 50 (C6), pp.C6-175-C6-175. �10.1051/jphyscol:1989629�. �jpa-00229660�
REWE DE PHYSIQUE APPLIQU~E
Colloque C 6 , Supplbment au n06, Tome 24, Juin 1989
SCANNING ISOTHERMAL CURRENT TRANSIENT SPECTROSCOPY (SICTS) FOR DEEP LEVEL CHARACTERIZATION
Y. TOKUMARU, H. OKUSHI* and H. NAKA"
Chuo University, Kasuga, Bunkyo-ku, Tokyo 112, Japan
*~lectrotechnical Laboratory, Umezono, Tsukuba, Ibaraki 305, Japan
X *
Micronics Japan Co., Ltd. Kichijoji-honcho, Musashino, Tokyo 180, Japan
We reported Isothermal Capacitance Transient Spectroscopy (ICTS), with which deep level signals can be obtained spectroscopically under
isothermal condition. ' ) ICTS was applied to the measurement of deep states in amorphous and crystalline semiconductors. 2.3' This method has an advantage : measurements are made at constant temperature.
Therefore, this method is considered to be more suitable for the microscopic spatial characterization than scanning DLTS. 4 '
In the present case, we measure current transient signals instead of capacitance transient ones and plot tI (t) vs t or tdI (t) /dt vs t (t is time and I is current). A peak appears at a time corresponding to the emission time constant of a deep level, whose height gives the density of the level. The measurement and signal processing are
performed with a computer-aided measurement system. Optical beam pulses from a semiconductor laser are used to fill the deep levels with
carriers and the specimen stage is moved mechanically for scanning with the optical beam.
We have applied this ICTS method to the characterization of gap states in undoped a-Si:H films. It has been found that the behavior of transient current I(t) agrees well with that of capacitance and I(t) is due to the thermally excited carriers (holes). SICTS measurement has been performed on the material and the gap state distribution has been obtained.
1) H. Okushi and Y. Tokumaru : Jpn. J. Appl. Phys. 21 (1981) Suppl.
20-1, p. 261.
2) H. Okushi : Philos. Mag. B 52 (1985) 33.
3) H. Tomokage, T. Miyamoto. H. Okushi and Y. Tokumaru : J. Appl. Phys.
62 (1987) 4806.
4) P.M. Petroff and D. V. Lang : Appl. Phys. Lett. 31 (1977) 60.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1989629
