Hi Alessandro,
first of all thanks a lot for your reply.
To 1):
actually this cantilever is just a very simple model for later simulations on a distributet bragg reflector membrane (3D with more than 30 layers each of a thickness of Lambda/4 with lambda=1.55µm optical wavelength)
Only the top layer will be conductive due to process techniques (PECVD layers are made of SiO_2 and SiN_x). The insulator characteristics of those layers should prevent a current flow from the upper to the bottom electrode in case of pull in. For the Force it should make only the difference that the capacity increases with those layers (epsilon_r) between the two electrodes and thus the electrostatical force increaes too with the factor epsilon_r which is quite nice (There is an applied voltage so V=const.) because it compensates slightly the larger spacing between the two electrodes (Force increases linearly with epsilon_r but decreases to 1/d^2 where d is the spacing / air gap).
To 2):
I set this high voltage because lower voltages didn't attract the cantilever (displacement was smaller than nm).
To 3):
Doesn't it make a big difference if you apply the force to the lower area of the cantilever instead to the top gold layer which the force is actually acting on? I mean the force at the bottom layer is much higher due to a smaller spacing between the two electrodes. Isn't it a completly different setup which is not compareable with mine? This would work only in the case of doped semi-conductive layers. But unfortunately it will be not possible doping them (for they will be replaced by SiO_2 and SiN_x. Doping for GaAs would be possible of course but is not preferred in the future).
To 4):
I completly agree with this point
I noticed that he is not able to find a solution for U = 0V have you any idea concerning this point? He neither can solve the model if I only solve the solid stress strain part. So I can not determine the bending of the cantilever in the rest position (caused by the different stress in the two layers).
Again: Thanks a lot Alessandro!
first of all thanks a lot for your reply.
To 1):
actually this cantilever is just a very simple model for later simulations on a distributet bragg reflector membrane (3D with more than 30 layers each of a thickness of Lambda/4 with lambda=1.55µm optical wavelength)
Only the top layer will be conductive due to process techniques (PECVD layers are made of SiO_2 and SiN_x). The insulator characteristics of those layers should prevent a current flow from the upper to the bottom electrode in case of pull in. For the Force it should make only the difference that the capacity increases with those layers (epsilon_r) between the two electrodes and thus the electrostatical force increaes too with the factor epsilon_r which is quite nice (There is an applied voltage so V=const.) because it compensates slightly the larger spacing between the two electrodes (Force increases linearly with epsilon_r but decreases to 1/d^2 where d is the spacing / air gap).
To 2):
I set this high voltage because lower voltages didn't attract the cantilever (displacement was smaller than nm).
To 3):
Doesn't it make a big difference if you apply the force to the lower area of the cantilever instead to the top gold layer which the force is actually acting on? I mean the force at the bottom layer is much higher due to a smaller spacing between the two electrodes. Isn't it a completly different setup which is not compareable with mine? This would work only in the case of doped semi-conductive layers. But unfortunately it will be not possible doping them (for they will be replaced by SiO_2 and SiN_x. Doping for GaAs would be possible of course but is not preferred in the future).
To 4):
I completly agree with this point
I noticed that he is not able to find a solution for U = 0V have you any idea concerning this point? He neither can solve the model if I only solve the solid stress strain part. So I can not determine the bending of the cantilever in the rest position (caused by the different stress in the two layers).
Again: Thanks a lot Alessandro!
