#### Builtin Voltage

p
```from math import log

from scipy.constants import Boltzmann, physical_constants

T = 300  # TEMPERATURE (unit = K)

def builtin_voltage(
donor_conc: float,  # donor concentration
acceptor_conc: float,  # acceptor concentration
intrinsic_conc: float,  # intrinsic concentration
) -> float:
"""
This function can calculate the Builtin Voltage of a pn junction diode.
This is calculated from the given three values.
Examples -
>>> builtin_voltage(donor_conc=1e17, acceptor_conc=1e17, intrinsic_conc=1e10)
0.833370010652644
>>> builtin_voltage(donor_conc=0, acceptor_conc=1600, intrinsic_conc=200)
Traceback (most recent call last):
...
ValueError: Donor concentration should be positive
>>> builtin_voltage(donor_conc=1000, acceptor_conc=0, intrinsic_conc=1200)
Traceback (most recent call last):
...
ValueError: Acceptor concentration should be positive
>>> builtin_voltage(donor_conc=1000, acceptor_conc=1000, intrinsic_conc=0)
Traceback (most recent call last):
...
ValueError: Intrinsic concentration should be positive
>>> builtin_voltage(donor_conc=1000, acceptor_conc=3000, intrinsic_conc=2000)
Traceback (most recent call last):
...
ValueError: Donor concentration should be greater than intrinsic concentration
>>> builtin_voltage(donor_conc=3000, acceptor_conc=1000, intrinsic_conc=2000)
Traceback (most recent call last):
...
ValueError: Acceptor concentration should be greater than intrinsic concentration
"""

if donor_conc <= 0:
raise ValueError("Donor concentration should be positive")
elif acceptor_conc <= 0:
raise ValueError("Acceptor concentration should be positive")
elif intrinsic_conc <= 0:
raise ValueError("Intrinsic concentration should be positive")
elif donor_conc <= intrinsic_conc:
raise ValueError(
"Donor concentration should be greater than intrinsic concentration"
)
elif acceptor_conc <= intrinsic_conc:
raise ValueError(
"Acceptor concentration should be greater than intrinsic concentration"
)
else:
return (
Boltzmann
* T
* log((donor_conc * acceptor_conc) / intrinsic_conc**2)
/ physical_constants["electron volt"][0]
)

if __name__ == "__main__":
import doctest

doctest.testmod()
```