Semiconductor Device and Method for Evaluating Semiconductor Device

摘要

A semiconductor layer with a low density of trap states is provided. A transistor with stable electrical characteristics is provided. A transistor having high field-effect mobility is provided. A semiconductor device including the transistor is provided. A method for evaluating a semiconductor layer is provided. A method for evaluating a transistor is provided. A method for evaluating a semiconductor device is provided. Provided is, for example, a semiconductor layer with a low defect density which can be used for a channel formation region of a transistor, a transistor including a semiconductor layer with a low defect density in a channel formation region, or a semiconductor device including the transistor.

主权项

1. An evaluation method for a semiconductor device comprising the steps of:
starting to apply a voltage between a first electrode and a second electrode at a time T0 so that a current flows in an oxide semiconductor layer electrically connected to the first electrode and the second electrode; irradiating the oxide semiconductor layer with light having an energy higher than an energy gap of the oxide semiconductor layer, wherein the irradiating step starts at a time T1 and stops at a time T2; comparing a value of a current flowing between the first electrode and the second electrode at a time T3 with a maximum value of a current flowing between the first electrode and the second electrode between the time T1 and the time T2; and comparing a value of a current flowing between the first electrode and the second electrode at a time T4 with the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2; and stopping to apply the voltage between the first electrode and the second at time T5, wherein the time T1 is after the time T0, wherein the time T3 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T1 and before the time T2, wherein the time T4 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T2, and wherein the time T5 is after the time T4.