import numpy as np
import matplotlib.pyplot as plt
# プロット範囲のxを用意
x = np.linspace(0.3,0.75,100)
# グラフ１は300度、グラフ2は350度
y1=(x-0.3)**0.5*np.exp(-x/(8.62e-5*300))
y2=(x-0.3)**0.5*np.exp(-x/(8.62e-5*350))
c1, c2 = "blue", "red"
l1,l2 = "room temperture", "high temperture"
fig, ax = plt.subplots()
ax.set_xlabel("energy from fermi level (V)")
ax.set_ylabel("electron number")
ax.set_title(r'electron in conduction band')
ax.plot(x, y1, color=c1, label=l1) 
ax.plot(x, y2, color=c2, label=l2) 
ax.legend()
plt.show()