Extraction of sub-gap density of states via capacitance-voltage measurement for the erasing process in a TFT charge-trapping memory

Yen Chang Chiang, Yang Hsuan Hsiao, Jeng Ting Li, Jen-Sue Chen

Research output: Contribution to journalArticle

Abstract

Charge-trapping memories (CTMs) based on zinc tin oxide (ZTO) semiconductor thin-film transistors (TFTs) can be programmed by a positive gate voltage and erased by a negative gate voltage in conjunction with light illumination. To understand the mechanism involved, the sub-gap density of states associated with ionized oxygen vacancies in the ZTO active layer is extracted from optical response capacitance-voltage (C-V) measurements. The corresponding energy states of ionized oxygen vacancies are observed below the conduction band minimum at approximately 0.5-1.0 eV. From a comparison of the fitted oxygen vacancy concentration in the CTM-TFT after the light-bias erasing operation, it is found that the pristine-erased device contains more oxygen vacancies than the program-erased device because the trapped electrons in the programmed device are pulled into the active layer and neutralized by the oxygen vacancies that are present there.

Original languageEnglish
Article number025319
JournalAIP Advances
Volume8
Issue number2
DOIs
Publication statusPublished - 2018 Feb 1

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electrical measurement
transistors
capacitance
trapping
oxygen
thin films
zinc oxides
tin oxides
electric potential
conduction bands
illumination
electrons
energy

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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title = "Extraction of sub-gap density of states via capacitance-voltage measurement for the erasing process in a TFT charge-trapping memory",
abstract = "Charge-trapping memories (CTMs) based on zinc tin oxide (ZTO) semiconductor thin-film transistors (TFTs) can be programmed by a positive gate voltage and erased by a negative gate voltage in conjunction with light illumination. To understand the mechanism involved, the sub-gap density of states associated with ionized oxygen vacancies in the ZTO active layer is extracted from optical response capacitance-voltage (C-V) measurements. The corresponding energy states of ionized oxygen vacancies are observed below the conduction band minimum at approximately 0.5-1.0 eV. From a comparison of the fitted oxygen vacancy concentration in the CTM-TFT after the light-bias erasing operation, it is found that the pristine-erased device contains more oxygen vacancies than the program-erased device because the trapped electrons in the programmed device are pulled into the active layer and neutralized by the oxygen vacancies that are present there.",
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Extraction of sub-gap density of states via capacitance-voltage measurement for the erasing process in a TFT charge-trapping memory. / Chiang, Yen Chang; Hsiao, Yang Hsuan; Li, Jeng Ting; Chen, Jen-Sue.

In: AIP Advances, Vol. 8, No. 2, 025319, 01.02.2018.

Research output: Contribution to journalArticle

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T1 - Extraction of sub-gap density of states via capacitance-voltage measurement for the erasing process in a TFT charge-trapping memory

AU - Chiang, Yen Chang

AU - Hsiao, Yang Hsuan

AU - Li, Jeng Ting

AU - Chen, Jen-Sue

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AB - Charge-trapping memories (CTMs) based on zinc tin oxide (ZTO) semiconductor thin-film transistors (TFTs) can be programmed by a positive gate voltage and erased by a negative gate voltage in conjunction with light illumination. To understand the mechanism involved, the sub-gap density of states associated with ionized oxygen vacancies in the ZTO active layer is extracted from optical response capacitance-voltage (C-V) measurements. The corresponding energy states of ionized oxygen vacancies are observed below the conduction band minimum at approximately 0.5-1.0 eV. From a comparison of the fitted oxygen vacancy concentration in the CTM-TFT after the light-bias erasing operation, it is found that the pristine-erased device contains more oxygen vacancies than the program-erased device because the trapped electrons in the programmed device are pulled into the active layer and neutralized by the oxygen vacancies that are present there.

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