L=(DT)^1/2 as a natural unit of length to characterise doffusion.擴散長度隨著T增大復合率而增加代表此為absorption lengrh 為一負指標。references[solar cellp.115]
電洞擴散係數(diffusion coefficient或diffusivity)定義為Dp=Dx^2/tc,電子擴散係數定義為Dn = D x^2 / tc。以矽為例,Dn = 34 cm^2/s,Dp = 13 cm^2/s。