a write transistor; and

a read transistor coupled to the write transistor, the write transistor and the read transistor coupled at a storage node, the storage node being for storing data;

wherein, at least one among the write transistor and the read transistor includes a threshold voltage adjusting layer, and a threshold voltage of the write transistor and/or the read transistor is adjustable, and the storage node is connected to a control terminal of the read transistor.