Unity2D script to programatcally add a sprite

I'm create a grid of tiles. The tiles are sprites and I'm laying them out programmatically. Here is the code to generate one of the tiles.

public Sprite tile_plain;  // assign this in unity by dragging a sprite to it

void Start()
{
  GameObject tile = new GameObject();
  tile.AddComponent();
  tile.GetComponent().sprite = tile_plain;
  tile.transform.position = new Vector2((i * tile_plain.rect.width)/tile_plain.pixelsPerUnit, 5f);
}