We report on a short wavelength p-i-n detector using InAs/GaAsSb type-Ⅱ superlattices(T2SL)with inserting AlSb layers.We use the 8K·P method to calculate the SL structure and Fig.1(a)shows the calculated energy levels of the electron and hole ground states together with the corresponding wave function distributions[1].According to our calculations,the e1-hh1 transition wavelength is 1.26 um,which coincides with the 1.22 um of the measured photoluminescence(PL)peak at 77 K [see Fig.1(b)].Fig.2(a)is the measured photocurrent spectrum at zero bias at 77 K.It can be seen that the response spectrum is a narrow-band type and reveals an asymmetric feature with a longer tail on the higher energy side.