Delphin Joseph The band gap of Mn-doped tin oxide remains constant despite varying doping concentrations, influenced by factors like Low Doping Concentration, and impurity effects.

It is important to check for impurities, optimize annealing conditions, and make precise measurements in order to overcome these problems.

Dear AS

Understanding Band Gap Variations:

• Doping Concentration: The band gap of semiconductors typically changes with doping concentration. In Mn-doped tin oxide, the expected trend is a decrease in band gap with increasing Mn concentration. However, if the Mn concentration is too low (0.010-0.030 mol%), the effect on the band gap might be negligible.
• Doping Mechanism: The doping mechanism can influence band gap variations. Substitutional doping (Mn replacing Sn) usually leads to band gap changes, while interstitial doping (Mn occupying empty spaces) might have minimal impact.
• Mn Oxidation State: The oxidation state of Mn can affect its electronic behavior and band gap influence. Depending on processing conditions, Mn might exist in multiple oxidation states, potentially canceling out band gap changes.
• Material Defects: Defects like vacancies, interstitials, or impurities can create localized energy states within the band gap, potentially masking the expected band gap shift from Mn doping.
• Measurement Technique: The accuracy and sensitivity of the measurement technique can affect the observed band gap. Ensure your method is suitable for the expected small changes at low doping levels.
• Valence Fluctuation: Mn ions can exhibit valence fluctuation, affecting the electronic behavior. Investigate whether this behavior contributes to the observed band gap variation.

Potential Solutions:

Sir actually I will dope Mn doped SnS 0.1 mole concentration (0.010 to 30 mole percentage) varey.. but no band gap changes.. bec 0.1 m so the dope is high.. so what do

Dear Alvena Shahid

Introducing Mn into the SnO2 lattice creates energy levels within the band gap and leads to a decrease/same. Mn atoms typically exist in multiple oxidation states, such as Mn²⁺ and Mn⁴⁺, in the SnO2 lattice. These d-orbitals of Mn are not completely filled with electrons and can participate in bonding with the surrounding oxygen and tin atoms in the lattice. This interaction introduces new energy levels within the band gap of SnO2, which previously consisted only of the valence and conduction bands formed by the Sn and O orbitals. When Mn substitutes for Sn in the lattice, it often creates a charge imbalance. Sn⁴⁺ has a higher valence (+4) compared to Mn²⁺ (+2). To maintain electrical neutrality, nearby electrons from the valence band of SnO2 can be excited to fill these newly introduced energy levels within the band gap. This excitation effectively reduces the energy needed to promote an electron from the valence band to the conduction band, leading to a narrower band gap or same.