matlab simple plotting with microseconds time vector

I have a exponentially decaying sinusoidal function which should decay in microseconds with frequency of 5 MHz.

function[t,x]=microsec(a, p, d, f) % microsec plots an oscillatory transient voltage disturbance % f = 5 MHz; % a is the magnitude of oscillatory disturbance component % p is the starting time of osillatory disturbance component in normal % voltage % d is the decay factor of oscillatory component f = 5000000; a = 1.0; p = 0.03; d = 55e4; t=0:0.1e-6:0.1; ff=50; %frequency of normal voltage x=sin(2*pi*ff*t)+ a*(u(t-p).*(exp(-d.*(t-p)))).*sin(2*pi*f*(t)); %exponentially decaying sinusoidal... %...transient element added to normal voltage plot(t,x) function y=u(t) % unit step function needed to decide the starting time of disturbance y=t>=0; end end

I expect this output:

But the resulting plot is not what I desired, it is blank up to the starting time of the disturbance:

Increasing the decay factor or oscillatory component frequency does not improve my result.
Someone told me, it is due to over-sampling. However, I didn’t get help on

1. How to plot a graph for microseconds range i.e. a sine wave of duration 0.1 sec
2. With a frequency of 50Hz
3. And a disturbance starting at 0.03 sec
4. And the disturbance itself being only microseconds in duration.