Keithley Series 2600 Application Manual Download

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5-7

SeCTIon 5

Using Substrate Bias

FET _ Comm _ Source _ Vsb(1, 12, 10, 1, 12,
80, –2)

to the instrument .

The sources will be enabled, and the substrate bias is applied,

10 .

the gate-source voltage value is applied, and the drain-source
sweep is executed . The gate-source voltage value is then incre-
mented and the drain-source sweep is re-run .
Once the gate-source sweep has been completed, the data

11 .

, V

, and I

) will be presented in the Instrument

Console window of TSB .

5.3.8 Typical Program 13 Results

Figure 5-6

shows a typical plot generated by Example

Program 13 .

5.3.9 Program 13 Description

Both instruments are returned to default conditions . Node 1
SMUB, which sweeps V

, is configured as follows:

Source V

•

1mA compliance, autorange

•

Local sense

•

vgsstart

•

: 0V

vgsstop

•

: 10V

vgssteps

•

: 5

Next, Node 1 SMUA, which sweeps V

and measures I

, is set up

to operate in the following manner:

Source V

•

Local sensing

•

100mA compliance, autorange measure

•

1 NPLC Line cycle integration

•

vdsstart

•

: 0V

vdsstop

•

: 10V

vdssteps

•

: 100

Finally, Node 2 SMUA, which provides substrate bias, is pro-
grammed as follows:

Source V

•

Local sensing

•

10mA compliance, autorange measure

•

Both instruments are returned to default conditions; the sources
are zeroed and enabled . The substrate bias (V

) and gate-source

) are applied and the program enters the main program loop

to perform five I

vs . V

sweeps, one for each of five V

values .

Node 1 SMUA then cycles through its sweep list, setting V

to the

required values, and measuring I

at each step along the way . The

program then loops back for the next sweep until all five sweeps
have been performed .

Next, all three SMU outputs are zeroed and disabled . Finally, the
data is written to the Instrument Console of the TSB .

5.3.10 Modifying Program 13

For different sweeps, the V

start, V

stop, V

steps, V

start,

stop, and V

steps values can be changed as required . For

different sweep lengths, array size and loop counter values must
be adjusted accordingly .

5.4 BJT Substrate Biasing

The following paragraphs discuss using one dual-channel and
one single-channel Series 2600 System SourceMeter instrument
to perform tests on a four-terminal device, such as a BJT, with
substrate bias . The example shown in this section is a modified
version of the common-emitter BJT test presented previously in
the guide .

5.4.1 Program 14 Test Configuration

Figure 5-7

shows the test configuration for Program 14 . Node 1

SMUB is used to sweep I

, while Node 1 SMUA sweeps V

and

measures I

. Node 2 SMUA applies the substrate bias (V

) to the

device under test .

5.4.2 example Program 14: Common-

emitter Characteristics with a

Substrate Bias

Program 14 demonstrates common-emitter characteristic test pro-
gramming with substrate bias . Proceed as follows:

With the power off, connect the dual-channel System Source-

1 .

Meter instrument to the computer’s IEEE-488 interface . Con-
nect the single-channel System SourceMeter instrument to the
dual-channel master using a crossover Ethernet cable .
Connect the test fixture to both units using appropriate

2 .

cables .
Turn on the instruments and allow the units to warm up for

3 .

two hours for rated accuracy .
Configure the TSP-Link communications for each instrument .

4 .

Slave:

A single-channel instrument such as the Model 2601,

2611, or 2635 .
1 . Press the MENU key to access MAIN MENU .