Ultrasonic Attenuation in n-Type Ge. I. Impurity Concentration Dependence

We report the dependence of the ultrasonic attenuation on the temperature, α( T ), in Sb doped Ge over the wide concentration ( N ) region 3.2×10 16 to 1.6×10 18 cm -3 which covers the critical concentration ( N c =1.5×10 17 cm -3 ) for the metal-insulator transition. The results can be classified as follows. In the region \(3.2× 10¹⁶{}N{<}6.9× 10¹⁶\) cm -3 , the behavior of α( T ) at \(T{}2\) K is similar to that observed in a lightly doped sample; in the region \(1.3× 10¹⁷{}N{}2.0× 10¹⁷\) cm -3 , α( T ) has a "shoulder", which has also been observed in Ge doped \(N{}4× 10¹⁷\) cm -3 As impurities by Ishiguro and Mikoshiba, For N >2×10 17 cm -3 , it is that predicted from a free electron gas model, and we obtained the intervalley scattering time τ i from α( T ). A discussion on the ultrasonic attenuation in the intermediate concentration region is given.