The answer is YES, and it can be performed using a wide range of technics. It depends of which kind of equipement you have!

For instance, aluminum can be evaporated, consequently you can performed "al contacts" through a shadow mask.

if you have lithographical equipement, you can: deposit aluminum and using lithography to obtain more precise "al contacts" size, and more accurate alignement of your OFET!

Tel us which kind of equipement you pocess.

good luck

feel free to contact me!

we have both thermal as well e-beam evaporation technique... I already tried using both these... using thermal the rate of aluminium is not constant then i tried e-beam evaporation, now i get constant rate which is the requirement for uniform film growth of Si wafer... when i put these deposited wafer in acetone for lift off for 10 or 15 min, i see my contacts are not good, some time even my flake disappear... PLZ give some suggestion... thankx 

If I understand well, your problem appears during lift off step. Which photoresist did you use. Which photoresist thickness did you have? Are you sure that your devellopement is completely done?

Have you some pictures? before and after lift off?

i used EL-9 and PMMA 950 (1000rotation/10sec and then 5000 rotation/30sec) and then baking for 10 minutes for both EL-9 and PMMA 950 procedure is same... later i made contacts using e-beam lithography and then developed for 15 second in MIBK and 10 sec in isopropanol... the contacts were fine as i observed when i used Cr/Au contacts fabrication... but this time i did Al only and the result was just disaster.... you can see from figure... some contact damage which also destroy my sample

Al adhesion on SiO2 is not so good. You can deposit very thin (3-4 nm) Cr before depositing Al. This will solve the adhesion problem for sure and you will get perfect lift-off. You just need to consider the Work function matching between Cr/Al to your channel materials. You need Ohmic contact and your carriers should tunnel through 3-4 nm Cr layer without a problem if your channel's work-function matches properly.