IEC 62951-2:2019 pdf download

IEC 62951-2:2019 pdf download.Semiconductor devices – Flexible and stretchable semiconductor devices
1 Scope
This part of IEC 62951 specifies terms, definitions, symbols, configurations and evaluation methods that can be used to evaluate and determine the performance characteristics of flexible thin-film transistor (TFT) devices. This document specifies test methods and characteristic parameters for accurately evaluating the performance and reliability in practical use of flexible TFT devices under the bending status.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses:  IEC Electropedia: available at http://www.electropedia.org/ ISO Online browsing platform: available at http://www.iso.org/obp 3.1 flexible thin-film transistor flexible TFT thin-film transistor fabricated on mechanically flexible substrates such as polymers and metal foils Note 1 to entry: This note applies to the French language only. 3.2 mobility <of an electron> quantity equal to the quotient of the modulus of the mean velocity of a charge carrier (electron) in the direction of an electric field by the modulus of the field strength [SOURCE: IEC 60050-521 :2002, 521 -02-58, modified — “electron” has been added.]3.4 threshold voltage gate-source voltage at which the magnitude of the drain current reaches a specified low value [SOURCE: IEC 60050-521 :2002, 521 -07-24] 3.5 gate voltage V GS voltage between gate and source 3.6 drain voltage V DS voltage between drain and source 3.7 drain current I DS current between drain and source 3.8 transconductance g m ratio of the increment in the drain current to a corresponding incremental change of the gate-source voltage with the drain-source voltage held constant [SOURCE: IEC 60050-521 :2002, 521 -07-25]
4 Test method
4.1 General To investigate the reliability of the flexible TFTs, bending tests are performed as follows (see Figure 1 ): a) prior to any bending, the electrical characteristics of the TFTs are measured; b) under the mechanical bending state, the electrical characteristics of the TFTs are re-measured as shown in Figure 3.4.2 Test of electrical characteristics before bending The stability test of a flexible TFT is carried out using four kinds of biased evaluation. The negative-bias-stress (NBS) test is carried out with a V GS of −20 V at a fixed V DS of 1 0 V under dark and the substrate temperature is maintained at 20 o C and 60 o C. The negative-bias-illumination-stress (NBIS) test is carried out with a V GS of −20 V at a fixed V DS of 1 0 V under illumination with a white light-emitting diode of 300 cd/m 2 brightness and the substrate temperature is maintained at 20 o C and 60 o C. The positive-bias-stress (PBS) test is carried out with a V GS of +20 V at a fixed V DS of 0,1 V under dark and the substrate temperature is maintained at 20 o C and 60 o C. The positive-bias-illumination-stress (PBIS) test is carried out with a V GS of +20 V at a fixed V DS of 0,1 V under illumination with a white light-emitting diode of 300 cd/m 2 brightness and the substrate temperature is maintained at 20 o C and 60 o C. In the test procedure, the drain current is measured at room temperature by sweeping the gate voltage from −30 V to 30 V, at a fixed drain voltage of 0,1 V. Afterwards, the device stability tests are performed for 3 h. The field-effect mobility shall be calculated using Formula (1 ). The mobility is extracted from the linear-regime transconductance g m at the low drain voltage of 0,1 V as follows: