A memory device includes a first conductor, a diode, a memory element, and a second conductor arranged in series. The diode includes a first semiconductor layer over and in electrical communication with the first conductor. A patterned insulating layer has a sidewall over the first semiconductor layer. The diode includes an intermediate semiconductor layer on a first portion of the sidewall, and in contact with the first semiconductor layer. The intermediate semiconductor layer has a lower carrier concentration than the first semiconductor layer, and can include an intrinsic semiconductor. A second semiconductor layer on a second portion of the sidewall, and in contact with the intermediate semiconductor layer, has a higher carrier concentration than the intermediate semiconductor layer. A memory element is electrically coupled to the second semiconductor layer. The second conductor is electrically coupled to the memory element.