High electron mobility in thin films formed via supersonic impact deposition of nanocrystals synthesized in nonthermal plasmas
High electron mobility in thin films formed via supersonic impact deposition of nanocrystals synthesized in nonthermal plasmas
复制标题
通过非热等离子体中合成的纳米晶体的超声冲击沉积形成的薄膜中的高电子迁移率
作者：
E. Thimsen;Melissa Johnson;Xin Zhang;Andrew J. Wagner;K. Mkhoyan;U. Kortshagen;E. Aydil
包含半导体纳米晶体的薄膜正在出现用于电子和光电器件（包括发光二极管和太阳能电池）的应用。在这些膜中实现高电荷载流子迁移率需要识别和消除在表面上的电子陷阱。在此，我们表明，在薄膜中包含ZnO纳米晶体，电子受体陷阱有关的表面上的OH的存在限制了导电性。以二乙基锌和氧气为原料，采用非热等离子体法合成了ZnO纳米薄膜，并通过惯性碰撞沉积在各种衬底上。令人惊讶的是，使用原子层沉积用几纳米的Al 2 O3涂覆ZnO纳米晶体使膜电阻率降低了7个数量级，其值低至0.12 Ω cm。在由涂覆有Al 2 O3的退火ZnO纳米晶体组成的薄膜中观察到电子迁移率高达3 cm 2 V-1 s-1。纳米材料中的表面缺陷可以捕获电子，从而限制电子器件的性能。Thimsen等人表明，包含ZnO纳米晶体的膜的电导率可以通过用Al 2 O3涂覆而增加。
Thin films comprising semiconductor nanocrystals are emerging for applications in electronic and optoelectronic devices including light emitting diodes and solar cells. Achieving high charge carrier mobility in these films requires the identification and elimination of electronic traps on the nanocrystal surfaces. Herein, we show that in films comprising ZnO nanocrystals, an electron acceptor trap related to the presence of OH on the surface limits the conductivity. ZnO nanocrystal films were synthesized using a nonthermal plasma from diethyl zinc and oxygen and deposited by inertial impaction onto a variety of substrates. Surprisingly, coating the ZnO nanocrystals with a few nanometres of Al2O3 using atomic layer deposition decreased the film resistivity by seven orders of magnitude to values as low as 0.12 Ω cm. Electron mobility as high as 3 cm2 V−1 s−1 was observed in films comprising annealed ZnO nanocrystals coated with Al2O3. Surface defects in nanomaterials can trap electrons and thereby limit the performance of electronic devices. Thimsen et al. show that the conductivity of films comprising ZnO nanocrystals can be increased by coating with Al2O3.