Transistors, methods of manufacturing the same and electronic devices including transistors

A method of manufacturing an oxide transistor, the method comprising:

• forming a channel layer on a substrate;
• forming a source electrode to contact a first end portion of the channel layer, and a drain electrode to contact a second end portion of the channel layer;
• forming a gate insulating layer to cover the channel layer, the source electrode, and the drain electrode;
• and
• forming a gate on the gate insulating layer;
• wherein
• the forming of the channel layer includes forming a first material layer and a second material layer sequentially on the substrate, the first material layer includes hafnium-indium-zinc-oxide (HfInZnO) and has a first electrical conductivity,
• the second material layer includes hafnium-indium-zinc-oxide (HfInZnO) and has a second electrical conductivity that is greater than the first electrical conductivity,
• the second material layer is closer to the gate than the first material layer,
• the first material layer and the second material layer have different metal composition ratios, and
• a zinc content of the first material layer is greater than a zinc content of the second material layer, the zinc content of the first material layer is between about 50 at % and about 87 at % based on the metallic components of the first material layer.

An oxide transistor comprising:

• a channel layer formed of an oxide semiconductor;
• a source electrode contacting a first end portion of the channel layer;
• a drain electrode contacting a second end portion of the channel layer;
• a gate corresponding to the channel layer;
• and
• a gate insulating layer disposed between the channel layer and the gate;
• wherein
• the oxide semiconductor includes hafnium-indium-zinc-oxide (HfInZnO),
• an electrical conductivity of a back channel region of the channel layer is lower than an electrical conductivity of a front channel region of the channel layer,
• the front channel region is closer to the gate than the back channel region, the back channel region and the front channel region have different metal composition ratios, and
• a zinc content of the back channel region is greater than a zinc content of the front channel region, the zinc content of the back channel region is between about 50 at % and about 87 at % based on the metallic components of the back channel region.