The caaccer freeze-out in strained p-Si1--Gex layers is studied analytically. It is found that as the Ge fraction increases

the valences effective densities of states（Nv）SiGe/（Nv）Si normlized bythat in Si decreases

furthermore

as the temperature beecomes lower

the decrease in （Nv）SiGe/（Nv）Si becomes more rapid. It is also shown that as the Ge fraction increases

although it has little effect on theionized doping concentration at room temperature

the ionias doping concentration inereases at low temperatures compared with that in Si. This implies that caaccer freeze-out is mitigated at low temperatures

which is beneficial to the operation of Sil-Gex-based devices at low temperatures.