What will be the de-Broglie wavelength associated with a particle with rest mass zero, if it is moving with a speed c?

The de-Broglie wavelength (λ) is given byλ=hp…(i)Where h is Planck's constant, p the momentum.Also, p=mv=m01−v2c2v… (ii)Where m0 is rest mass, v the velocity and c the speed of light.From Eqs. (i) and (ii), we getλ=h1−v2c2m0vGiven, v=c ∴λ=0