Diode Temperature-Voltage Characteristics

Download the Python libraries voetsch.py and KeithleyV15.py and save them in your directory. Put the following script in the same directory.

from voetsch import VT4002
from KeithleyV15 import SMU26xx
import matplotlib.pyplot as plt
import time
import datetime
import csv
import numpy as np

""" ******* Configure the VT4002 climate chamber ******** """

# define connection parameters
ip_address = "129.27.158.42"
username = "user_name"   # fill in the username on the front of the climate chamber
password = "password"   # fill in the password on the front of the climate chamber

climate_chamber = VT4002(ip_address, username, password)

climate_chamber.enable()

""" ******* Connect to the Sourcemeter ******** """

# initialize the Sourcemeter and connect to it
# you may need to change the IP address depending on which sourcemeter you are using
sm = SMU26xx("TCPIP0::129.27.158.13::inst0::INSTR")

# get one channel of the Sourcemeter (we only need one for this measurement)
smu = sm.get_channel(sm.CHANNEL_A)

""" ******* Configure the SMU Channel A ******** """

# reset to default settings
smu.reset()
# setup the operation mode
smu.set_mode_current_source()
# set the voltage and current parameters
smu.set_voltage_range(2)
smu.set_voltage_limit(2)
smu.set_voltage(0)
smu.set_current_range(1E-5)
smu.set_current_limit(1E-5)
bias_current = 1E-6
smu.set_current(bias_current)
smu.display_voltage()

""" ******* For saving the data ******** """

# Create unique filenames for saving the data
time_for_name = datetime.datetime.now().strftime("%Y_%m_%d_%H%M%S")
filename_csv = 'VvsT' + time_for_name +'.csv'
filename_pdf = 'VvsT' + time_for_name +'.pdf'

# Header for csv
with open(filename_csv, 'a') as csvfile:
        writer = csv.writer(csvfile, delimiter=';',  lineterminator='\n')
        writer.writerow(["Voltage / V", "Temperature / C", "Current / A"])

""" ******* Define voltage-sweep paramters ******** """

# define sweep parameters
sweep_start = 10
sweep_end = 60

# define variables we store the measurement in
data_temperature = []
data_voltage = []
data_current = []

# enable the output
smu.enable_output()

""" ******* Sweep the temperature ******** """

for T in range(sweep_start,sweep_end):
    temp = climate_chamber.get_actual_temperature()
    print('Temperature (°C): ' + str(temp))
    
    climate_chamber.go_to_temperature(T, 0.2, 60)

#Read out the current temperature and print the result to the console
    temp = climate_chamber.get_actual_temperature()
    print(' ')
    print('Temperature (°C): ' + str(temp))

#get current and voltage from the SMU and append it to the list so we can plot it later
    [current, voltage] = smu.measure_current_and_voltage()
    data_voltage.append(voltage)
    data_current.append(current)
    data_temperature.append(temp)
    print(str(voltage)+' V; '+str(temp)+' C; '+str(current)+' A')
    # Write the data in a csv
    with open(filename_csv, 'a') as csvfile:
        writer = csv.writer(csvfile, delimiter=';',  lineterminator='\n')
        writer.writerow([voltage, temp, current])

# disable sourcemeter output
smu.disable_output()

# properly disconnect from the device
sm.disconnect()

""" ******* Plot the Data we obtained ******** """

plt.plot(data_temperature, data_voltage, 'x-', linewidth=2)

# set labels and a title
plt.xlabel('Temperature / C', fontsize=14)
plt.ylabel('Voltage / V', fontsize=14)
plt.title('Temperature-Voltage characteristic of a diode', fontsize=14)
plt.tick_params(labelsize = 14)

plt.savefig(filename_pdf)
plt.show()

#Bring the climate chamber to room temperture so you can safely open it
climate_chamber.go_to_temperature(20, 2, 60)

climate_chamber.disable()

sweep_diode_temperature.py sweep_diode_temperature_2SMU.py

In this script, first the climate chamber and the sourcemeter are initialized. The sourcemeter is set to current source mode and a current of 1 μA is set. The bias current should be small enough that it does not cause the diode to heat up. The script then steps through a temperature range recording the voltage across the diode at every temperature. There is also a version for measuring two diodes with two SMUs.

The temperature-voltage characteristice of a BZX85 Zener diode with bias currents of 1 μA and 10 μA are shown below. The characterisitic is nearly linear.







Semiconductor Laboratory