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NEET Physics Semiconducting Devices NEET PYQ-Semiconducting Devices

  • question_answer
    Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by \[{{({{E}_{g}})}_{C}},\] \[{{({{E}_{g}})}_{Si}}\] and \[({{E}_{g}}){{G}_{Ge}}\] respectively. Which one of the following relationships is true in their case?                                           [AIPMT (S) 2005]

    A) \[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Si}}\]

    B)       \[{{({{E}_{g}})}_{C}}={{({{E}_{g}})}_{Si}}\]

    C)  \[{{({{E}_{g}})}_{C}}<({{E}_{g}})Ge\]         

    D)  \[{{({{E}_{g}})}_{C}}<{{({{E}_{g}})}_{Si}}\]

    Correct Answer: A

    Solution :

    Carbon, silicon and germanium are semiconductors.
                \[{{({{E}_{g}})}_{C}}=5.2\,eV\]
                \[{{({{E}_{g}})}_{Si}}=1.21\,eV\]
                \[{{({{E}_{g}})}_{Ge}}=0.75\,eV\]
    Thus, \[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Si}}\] and \[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Ge}}\]
    Note:    Elements carbon, silicon and germanium are found in IVA group of periodic table.


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