Suppose a pure Si crystal has \( 5 \times 10^{28} \) atoms \( m ^{-3} \). It is doped by a 1 ppm concentration of pentavalent As. The number of electrons and holes are, respectively:
(Given that \( n _{ i }=1.5 \times 10^{16} m ^{-3} \) )
1. \( 5 \times 10^{22} / m ^{3}, 4.5 \times 10^{9} / m ^{3} \)
2. \( 4.5 \times 10^{9} / m ^{3}, 5 \times 10^{22} / m ^{3} \)
3. \( 5 \times 10^{22} / m ^{3}, 5 \times 10^{22} / m ^{3} \)
4. \( 4.5 \times 10^{9} / m ^{3}, 4.5 \times 10^{9} / m ^{3} \)