Standards Development

Scope

This part of IEC 62876 establishes a standardized guideline to assess reliability of metal contacts in field - effect transistors (FETs) formed by using semiconducting 2D materials. From assessing linea rity of output I- V curves at various conditions such as gate voltage and temperature, stability and processing window of FETs can be determined. The objectives of this standard are to

• determine stability of FETs, from assessing linearity of output I -V curves at various conditions

• investigate stability and processing window of FETs by varying 2D materials, contacting metal, channel thickness, applied voltage, and annealing condition

• apply this standard to various cases of widely investigated 2D mate rials (eg. graphene, MoS2, WS2, WSe2, etc) and metals (eg. Ti, Cr, Au, Pd, etc).and

• establish the minimum reporting requirements.

Purpose

Atomically thin two dimensional (2D) materials are expected to be used for future electrical sub -systems or electronic device applications.

- I–V measurement is the fundamental electrical characterization technique for assessing reliability of field - effect transistors (FETs) as well as semiconductor device performance.

- If metallic contact has negligible effects on electronic transport, output characteristics show a linear behavior, which can be interpreted as Ohmic contact. In contrast, when metallic con tact has strong effects on electronic transport, output characteristics no longer show the linear behavior, according to the following formula, which is interpreted as Schottky contact which can bring about a reliability issue of semiconductor transistor operation.

- Current transport at the metallic contact of 2D material -based FETs is found to be affected significantly by van der Waals surface forming an interface with a contacting metal. That is, the metal -2D semiconductor interface involves van der Waals gap which creates a high contact resistance and suppresses current transport of the 2D FETs.

- The high contact resistance and suppressed current transport are also affected by the unavailability of efficient doping techniques for 2D materials at the m etal-semiconductor junction, which is different from 3D bulk semiconductors using conventional semiconductor materials such as silicon.

- Therefore, it is important to obtain accurate I-V characteristics and to assess linearity of the I-V curves, so that reliable 2D FET device operation can be ensured.