From 742e0bdd18bdbaa20d54b59565b42b18531ef226 Mon Sep 17 00:00:00 2001
From: Kostas Vilkelis <kostasvilkelis@gmail.com>
Date: Fri, 26 Mar 2021 14:18:56 +0000
Subject: [PATCH] this the bug?

---
 src/14_doping_and_devices.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/14_doping_and_devices.md b/src/14_doping_and_devices.md
index 004fe38f..27ab295c 100644
--- a/src/14_doping_and_devices.md
+++ b/src/14_doping_and_devices.md
@@ -63,9 +63,9 @@ $$
 However, the extra valance electron moves in the semiconductor's conduction band and not free space.
 Therefore, the electron's mass is the conduction band's effective mass. 
 Furthermore, the interactions between the electron and proton are screened by the lattice.
-As a result, we need to introduce the following substitutions: $m_e \to m_e^*$, $\epsilon_0 \to \epsilon\epsilon_0$.
+As a result, we need to introduce the following substitutions: $m_e \to m_e$, $\epsilon_0 \to \epsilon\epsilon_0$.
 We thus estimate the energy of the bound state created by the impurity:
-$$E = -\frac{m_e^*}{m_e \varepsilon^2} R_E = -0.01 \text{eV (in Ge)},$$
+$$E = -\frac{m_e}{m_e \varepsilon^2} R_E = -0.01 \text{eV (in Ge)},$$
 with Bohr radius $r_B = 4$ nm (vs $r_B = 0.5$ Ã… in Hydrogen).
 The electron is very weakly bound to the impurity!
 At room temperature (0.026 eV), the donor electron is easily thermally excited into the conduction band. 
-- 
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