code: def plot_hall_carriers(self, temp=300):
          
          import matplotlib.pyplot as plt
          hall_carriers = [abs(i) for i in
                           self._bz.get_hall_carrier_concentration()[temp]]
          plt.semilogy(self._bz.mu_steps,
                       hall_carriers,
                       linewidth=3.0, color='r')
          self._plot_bg_limits()
          self._plot_doping(temp)
          plt.xlim(-0.5, self._bz.gap + 0.5)
          plt.ylim(1e14, 1e22)
          plt.ylabel("Hall carrier concentration (cm-3)", fontsize=30.0)
          plt.xlabel("E-E$_f$ (eV)", fontsize=30)
          plt.xticks(fontsize=25)
          plt.yticks(fontsize=25)
          return plt
docs: Plot the Hall carrier concentration in function of Fermi level
  
          Args:
              temp: the temperature
  
          Returns:
              a matplotlib object