In Python, 1j or 0+1j is a literal of complex type. You can broadcast that into an array using expressions, for example
In [17]: 1j * np.arange(5)
Out[17]: array([ 0.+0.j, 0.+1.j, 0.+2.j, 0.+3.j, 0.+4.j])
Create an array from literals:
In [18]: np.array([1j])
Out[18]: array([ 0.+1.j])
Note that what Michael9 posted creates a complex, not a complex array:
In [21]: np.complex(0,1)
Out[21]: 1j
In [22]: type(_)
Out[22]: complex