Diode Measurement

IV/CV measurements for silicon sensors.

Run

On Windows download a pre-built executable from the release section and run it.

Install

Install using pip in a virtual environment.

pip install git+https://github.com/hephy-dd/diode-measurement.git@{version}

Build Executable

Building a Windows executable using PyInstaller.

# Create build environment
python -m venv build_env
. build_env/Scripts/activate

# Install dependencies
pip install -U pip
pip install wheel pyusb pyserial gpib-ctypes
pip install pyinstaller==4.10.* pyinstaller-versionfile==2.0.*
pip install .

# Build executable
pyinstaller pyinstaller.spec

An executable will be created in dist/diode-measurement-{version}.exe

Supported Instruments

Source Meter Units

• Keithley K237
• Keithley K2410
• Keithley K2470
• Keithley K2657A

Electro Meter

• Keithley K6514
• Keithley K6517B

LCR Meter

• Keithley K595
• Keysight E4980A
• Agilent 4284A

DMM (Temperature)

• Keithley K2700

Switching Matrix

• HEPHY BrandBox (HV Switch)

Setup

To interface instruments using a GPIB interface the NI-VISA drivers need to be installed. Interfacing instruments using TCPIP, USB or Serial port is supported out of the box by using PyVISA-py, pyusb and pyserial.

The instrument resource name inputs accept follwing formats:

Format	Example	Result
<n>	16	GPIB::16::INSTR
<ip>:<port>	0.0.0.0:1080	TCPIP::0.0.0.0::1080::SOCKET
<host>:<port>	localhost:1080	TCPIP::localhost::1080::SOCKET
<visa>	GPIB1::16::INSTR	GPIB1::16::INSTR

Data formats

The used plain text format consists of a header containing meta data in key and value pairs and one or more CSV data tables with headers using \t separators.

Synopsis

<key>: <value>
...
<<series>[<unit>]\t...>
<<value>\t...>
...

IV

IV measurement data consist of up to two CSV tables with the second (optional) table containing continuous measurement data.

Example

sample: Unnamed
measurement_type: iv
voltage_begin[V]: +5.000E+00
voltage_end[V]: -1.000E+01
voltage_step[V]: +1.000E+00
waiting_time[s]: +1.000E-01
current_compliance[A]: +1.000E-06

timestamp[s]	voltage[V]	v_smu[V]	i_smu[A]	i_elm[A]	i_elm2[A]	temperature[degC]
1629455368.29	+5.000E+00	+5.038E+00	+4.261E-08	+3.740E-08	+NAN	+NAN
1629455369.71	+4.000E+00	+4.065E+00	+7.708E-08	+9.495E-08	+NAN	+NAN
1629455370.49	+3.000E+00	+3.007E+00	+3.460E-08	+6.264E-08	+NAN	+NAN
...          	...       	...       	...       	...       	...       	...

timestamp[s]	voltage[V]	v_smu[V]	i_smu[A]	i_elm[A]	i_elm2[A]	temperature[degC]
1629455385.69	+3.000E+00	+3.046E+00	+3.996E-04	+7.137E-08	+NAN	+NAN
1629455387.65	+3.000E+00	+3.034E+00	+7.353E-04	+3.079E-08	+NAN	+NAN
1629455389.56	+3.000E+00	+3.021E+00	+9.081E-04	+1.266E-08	+NAN	+NAN
...          	...       	...       	...       	...       	...       	...

IV Bias

IV bias measurement data consist of up to two CSV tables with the second (optional) table containing continuous bias measurement data.

Example

sample: Unnamed
measurement_type: iv_bias
bias_voltage[V]: +1.000E+01
voltage_begin[V]: +5.000E+00
voltage_end[V]: -1.000E+01
voltage_step[V]: +1.000E+00
waiting_time[s]: +1.000E-01
current_compliance[A]: +1.000E-06

timestamp[s]	voltage[V]	v_smu[V]	i_smu[A]	v_smu2[V]	i_smu2[A]	i_elm[A]	i_elm2[A]	temperature[degC]
1629455368.29	+5.000E+00	+5.038E+00	+4.261E-08	+1.063E+01	+3.723E-08	+3.740E-08	+NAN	+NAN
1629455369.71	+4.000E+00	+4.065E+00	+7.708E-08	+1.051E+01	+6.513E-08	+9.495E-08	+NAN	+NAN
1629455370.49	+3.000E+00	+3.007E+00	+3.460E-08	+1.058E+01	+2.410E-08	+6.264E-08	+NAN	+NAN
...          	...       	...       	...       	...       	...       	...       	...       	...

timestamp[s]	voltage[V]	v_smu[V]	i_smu[A]	v_smu2[V]	i_smu2[A]	i_elm[A]	i_elm2[A]	temperature[degC]
1629455385.69	+3.000E+00	+3.046E+00	+3.996E-08	+1.063E+01	+2.657E-08	+7.137E-08	+NAN	+NAN
1629455387.65	+3.000E+00	+3.034E+00	+7.353E-08	+1.063E+01	+6.154E-08	+3.079E-08	+NAN	+NAN
1629455389.56	+3.000E+00	+3.021E+00	+9.081E-08	+1.063E+01	+8.426E-08	+1.266E-08	+NAN	+NAN
...          	...       	...       	...       	...       	...       	...       	...       	...

CV

CV measurement data consist of a single CSV table containing the measurement data.

Example

sample: Unnamed
measurement_type: cv
voltage_begin[V]: +5.000E+00
voltage_end[V]: -1.000E+01
voltage_step[V]: +1.000E+00
waiting_time[s]: +1.000E-01
current_compliance[A]: +1.000E-08

timestamp[s]	voltage[V]	v_smu[V]	i_smu[A]	c_lcr[F]	c2_lcr[F]	r_lcr[Ohm]	temperature[degC]
1629455368.29	+5.000E+00	+5.065E+00	+4.261E-08	+3.740E-05	7.149E+08	3.459932E-01	+NAN
1629455369.71	+4.000E+00	+4.037E+00	+7.708E-08	+9.495E-05	1.109E+08	3.015286E-01	+NAN
1629455370.49	+3.000E+00	+3.043E+00	+3.460E-08	+6.264E-05	2.549E+08	2.482018E-01	+NAN
...          	...       	...       	...       	...      	...      	...

JSON-RPC

The application provides an JSON-RPC (remote procedure call) version 2.0 interface using a TCP server.

Methods

Start

Start notification starts a new measurement.

{"jsonrpc": "2.0", "method": "start"}

Optional parameters are continuous (Boolean), reset (Boolean), auto_reconnect (Boolean), begin_voltage (Volt), end_voltage (Volt), step_voltage (Volt), waiting_time (seconds), compliance (Ampere) and waiting_time_continuous (seconds). Specified values will be applied to the user interface before starting the measurement.

{
  "jsonrpc": "2.0",
  "method": "start",
  "params": {
    "reset": true,
    "end_voltage": -100.0,
    "step_voltage": 10.0,
    "waiting_time": 1.0
  }
}

Stop

Stop notification stops an active measurement.

{"jsonrpc": "2.0", "method": "stop"}

Change voltage

Change voltage notification applies only during continuous It measurement.

Required parameter end_voltage (Volt).

Optional parameters with default values are step_voltage (default is 1.0 Volt) and waiting_time (default is 1.0 seconds).

{
  "jsonrpc": "2.0",
  "method": "change_voltage",
  "params": {
    "end_voltage": 100.0,
    "step_voltage": 10.0,
    "waiting_time": 0.25
  }
}

State

Request an application state snapshot.

{"jsonrpc": "2.0", "method": "state", "id": 0}

This will return application state parameters.

{
  "jsonrpc": "2.0",
  "result": {
    "state": "ramping",
    "measurement_type": "iv",
    "sample": "VPX1",
    "source_voltage": 24.0,
    "smu_voltage": 24.026,
    "smu_current": 0.0025,
    "smu2_voltage": null,
    "smu2_current": null,
    "elm_current": 0.0021,
    "elm2_current": null,
    "lcr_capacity": null,
    "temperature": 24.031
  },
  "id": 0
}

States

Following states are exposed by the state snapshot: idle, configure, ramping, continuous, stopping.

Example

Example using netcat to initiate a new measurement and applies a new end voltage.

echo '{"jsonrpc": "2.0", "method": "start", "params": {"end_voltage": 100.0}}' | nc localhost 8000

Example using Python to read application state from TCP server.

import json
import socket

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    sock.connect(('localhost', 8000))
    request = {
      "jsonrpc": "2.0",
      "method": "state",
      "id": None
    }
    sock.sendall(json.dumps(request).encode('utf-8'))
    print(sock.recv(4096).decode('utf-8'))