What will be the fragment shader for SNORM textures? If i want to use GL_TEXTURE_2D_ARRAY as a target then which type of sampler variable should be used (i,u) ?

I am getting enuexpected behaviour with following fragment shader:

Code :
 in vec3 ps_texCoord;
    uniform sampler2DArray tk_diffuseMap;
    out vec4 fragColor;
    void main()
    {
     fragColor = texture(tk_diffuseMap, ps_texCoord);
     }