JPS5972178A - Measuring method for gaas field effect transistor - Google Patents

Abstract

PURPOSE:To facilitate the measurement of GaAs FET instabilities by a method wherein measurement is made of the breakdown voltage across gate and drain to replace measurement of changes in characteristics before and after an excess input at high frequencies. CONSTITUTION:A multiplicity of GaAs FETs of the same structure is used to establish correlation between the variation (dB) in low power gain before and after an excessive high frequency input and the breakdown voltage V(BR)GDOV across gate and drain. When the breakdown voltage V(BR)GDO is determined by using the correlation thus established, variation (dB) in the low power gain before and after an excessive high frequency input can be obtained by calculation only. The variation thus determined by calculation is not correct but near correct due to fluctuations present in the correlation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring GaAs field effect transistors.

2. Description of the Related Art Conventionally, GaAs square junction field effect transistors have been used as electronic devices at extremely high frequencies because GaAs, the basic material thereof, has high carrier mobility. Furthermore, in order to obtain somewhat superior electrical characteristics at high frequencies, it is essential that the gate length be extremely fine, and at present, 0.5 to 1.0 μm is often used. Sara K.

During operation, the length of the depletion layer extending from the gate in the channel in the channel direction (effective gate length) is longer than this, so a structure with a thinner channel thickness is also required. The channel thickness has a value of 1000 to aoooX. In addition, due to the material properties of GBAs, a complete surface protection film cannot be obtained, so the 1 surface state is generally inferior to 8i devices, which can form excellent films such as Si02 and Si3N4. It is stable.

An example of a malfunction caused by the thin channel thickness and surface instability mentioned above in actual use is when an excessive input signal is received or an excessive output is generated. The problem is that the operating characteristics change. for example,
In a certain GaAs field effect transistor, the power gain when outputting 30dBm (1W) is 1Q as an initial value.
dB (the input signal is 20 dBm), when this input signal is increased by 3 dB, the output power is about 33 dBm, and the primary input voltage is returned to 20 dBm, the output voltage is 29 dBm.

This is a situation in which the power gain decreases by 1 dB.

The detailed cause of this phenomenon is not clear, but the maximum power of 2W is the voltage of IOV in a 50Ω load system, and this voltage is added to the gate-drain voltage of the DC bias. The voltage between the drains approaches the breakdown state,
It is presumed that this is because the high-energy charges generated at this time are dragged near the surface and change the state of the channel, for example, the effective channel thickness.

The instability of a G a AS field effect transistor has conventionally been measured by examining the presence or absence of characteristic fluctuations before and after an excessive input at high frequencies. However, measurements using high frequencies have the disadvantage of requiring a great deal of effort.

The present invention eliminates the above-mentioned drawbacks and makes it possible to easily measure the instability of a GaAs field effect transistor with less man-hours by replacing the measurement of characteristic fluctuations before and after an excessive input at high frequencies with the measurement of the gate-drain breakdown voltage. The present invention provides a method for measuring GaAs field effect transistors that can be used.

The method for measuring a GaAs field effect transistor of the present invention is as follows:
The correlation between the amount of change in the low power operating characteristics of the GaAs field effect transistor before and after applying a high-frequency overinput signal or high-frequency overoutput and the gate-drain breakdown voltage is determined in advance, and the gate-drain breakdown voltage is measured. The present invention is characterized in that the amount of change in the low power operating characteristic before and after the application of a high frequency over-input signal or the high-frequency over-output is calculated from the above-mentioned correlation.

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a distribution diagram showing an example of the correlation between the gate-drain breakdown voltage of a GaASt field effect transistor and the amount of change in low power gain before and after high frequency overpower.

A plurality of G a As field effect transistors with the same structure are prepared, and the amount of change in low power gain (dB) before and after high frequency overoutput and the breakdown voltage V (BR) between gate Φ and drain are calculated.
Figure 2 shows the correlation with GDO (Vl). From this correlation, if we measure the drop voltage V (dish) GDO, we can calculate the amount of change in low power gain before and after high frequency over-output. Since there is some variation in the correlation, the amount of change obtained from the calculation is not strictly accurate, but a value close to the exact value can be obtained.Practically speaking, this is sufficient.As mentioned above, Measurements using high frequencies require a great deal of effort, but since gate-source breakdown voltage can be measured using direct current, the measurement effort is extremely small.
And easy.

Although the above embodiment deals with the case of high frequency withdrawal output, a similar correlation can be obtained even in the case of high frequency excessive input.

According to one aspect of the present invention, as described in detail above.

The effect is significant because high-frequency measurements, which require a lot of labor, can be replaced with direct current measurements, which require less labor.

[Brief explanation of the drawing]

FIG. 1 is a distribution diagram showing an example of the correlation between the gate-drain breakdown of a GaAs field effect transistor and the amount of change in low power gain before and after high frequency overpower.

Claims (1)

[Claims] The correlation between the amount of change in the low power operating characteristics of a GaAs field effect transistor before and after the application of a high-frequency overinput signal or high-frequency overoutput and the breakdown voltage between the gate and drain is determined in advance, and the breakdown voltage between the gate and drain is determined in advance. A method for measuring a GaAs field effect transistor, characterized in that the amount of change in low power operating characteristics before and after application of a high frequency overinput signal or high frequency overoutput is calculated from the measured value from the correlation.