Black phosphorus (BP) has been gathering great attention for its electronic and optoelectronic applications due to its high electron mobility and high ION/OFF current switching ratio. The limitations of this material include its low synthetic yield and high cost. One alternative to BP is another type of phosphorus allotrope, red phosphorus (RP), which is much more affordable and easier to process. Although RP has been widely used in industry for hundreds of years and considered as an insulating material, in this study, we demonstrate through field‐effect transistors (FET) measurements that amorphous red phosphorus (a‐RP) films are semiconductive with a high mobility of 387 cm2 V−1 s−1 and a current switching ratio of ≈103, which is comparable to the electronic characteristics previously reported for BP. The films were produced via a thermal evaporation method or a facile drop‐casting approach onto Si/SiO2 substrates. We also report a study of the oxidation process of the films over time and a method to stabilize the films via doping a‐RP with metal oxides. The doped films retain stability for one thousand I–V cycles, with no signs of degradation.

Blackp hosphorus (BP) has been gathering great attention for its electronic and optoelectronic applications due to its high electron mobility and high I ON/OFF current switching ratio.T he limitations of this material include its low synthetic yield and high cost. One alternative to BP is another type of phosphorus allotrope,r ed phosphorus (RP), which is much more affordable and easier to process.A lthough RP has been widely used in industry for hundreds of years and considered as an insulating material, in this study,wedemonstrate through field-effect transistors (FET) measurements that amorphous red phosphorus (a-RP) films are semiconductive with ah igh mobility of 387 cm 2 V À1 s À1 and ac urrent switching ratio of % 10 3 ,w hich is comparable to the electronic characteristics previously reported for BP.T he films were produced via at hermal evaporation method or af acile drop-casting approach onto Si/SiO 2 substrates.W ea lso report as tudy of the oxidation process of the films over time and am ethod to stabilizet he films via doping a-RP with metal oxides.T he doped films retain stability for one thousand I-V cycles,w ith no signs of degradation.Phosphorus exhibits aw ide variety of allotropes,which can be divided into three distinct groups:w hite,b lack, and red phosphorus.T hese three groups have been known for hundreds of years, [1] but their crystal structures were only described in the last century.W hite phosphorus,d efined as the standard state of phosphorus (even though it is not the most thermodynamically stable), is ac rystalline four-atoms cage arrangement of phosphorus (P 4 ), and exists in three different arrangements (a-, b-and g-P 4 ). [2,3] Black phosphorus (BP) exists in an amorphous form [4] and three known different crystalline phases (orthorhombic,c ubic and rhombohedral). [5][6][7][8] Orthorhombic BP is the most thermodynamically stable BP allotrope and its crystal structure consists of layers held by van der Waals forces,which exhibits flakiness similar to graphite. [9][10][11][12] Bulk BP has aband gap of % 0.3 eV; as the layer number is decreased, quantum confinement effects increase that value to as high as 1.5 eV for monolayer phosphorene. [13][14][15] This tunability makes BP suitable for aw ide variety of electronic and optoelectronic applications.F ew-layer BP is ap -type charge carrier with mobilities as high as 1000 cm 2 V À1 s À1 . [16] 2D BP nanomaterials used in optoelectronic devices to date are typically prepared by two methods.T he first involves manual delamination of bulk crystals and subsequent transfer to as ubstrate, [10] as was originally employed for the isolation of graphene.H owever, this is an extremely low throughput strategy and offers little hope for scalable device integration. Thesecond method involves ultrasonic delamination of abulk BP crystal to form as uspension of few-layer fragments,w ith asubsequent solution-deposition step to form athin film. [17][18][19] Thed rawbacks of this method include 1) the solvent and ultrasound can introduce defects;2 )t ...