How to movement like Input.GetAxis("Horizontal") with touch? C#

I need movement like Input.GetAxis("Horizontal") for my 3D android game.

i have a script, but there the player move very fast and not smooth enought. How can i earn smooth movement with touch? I only need horizontal.

public float speed = 2f;

void FixedUpdate () {

 if(Input.touchCount ==1)
     {

         Touch touch = Input.touches [0];
         if (touch.position.x < Screen.width / 2) {


             transform.position += Vector3.left * speed * Time.deltaTime;

         } else if (touch.position.x > Screen.width / 2) {

         //    transform.position += Vector3.right * speed * Time.deltaTime;
         }