When arsenic is added as an impurity to silicon,the resulting material is

Donor type impurity is found in

Indium impurity is added to a sample of $Si$ to prepare a $p$-type semiconductor. In this semiconductor,one atom of indium is added per $5 \times 10^7$ atoms of $Si$. The atomic density of the $Si$ sample is $5 \times 10^{28} \text{ atoms/m}^3$. How many acceptor atoms will be present in a $1 \text{ cm}^3$ cube of silicon?

In $n$-type semiconductor,which of the following statements is true?

In a $p$-type semiconductor,

$A$ semiconductor has equal electron and hole concentration of $2 \times 10^8 \ m^{-3}$. On doping with a certain impurity,the electron concentration increases to $4 \times 10^{10} \ m^{-3}$. What is the new hole concentration of the semiconductor?